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* remove abs64()Andrew Morton2015-11-092-2/+2
| | | | | | | | | | | | | | | Switch everything to the new and more capable implementation of abs(). Mainly to give the new abs() a bit of a workout. Cc: Michal Nazarewicz <mina86@mina86.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'akpm' (patches from Andrew)Linus Torvalds2015-11-0714-76/+45
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge second patch-bomb from Andrew Morton: - most of the rest of MM - procfs - lib/ updates - printk updates - bitops infrastructure tweaks - checkpatch updates - nilfs2 update - signals - various other misc bits: coredump, seqfile, kexec, pidns, zlib, ipc, dma-debug, dma-mapping, ... * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (102 commits) ipc,msg: drop dst nil validation in copy_msg include/linux/zutil.h: fix usage example of zlib_adler32() panic: release stale console lock to always get the logbuf printed out dma-debug: check nents in dma_sync_sg* dma-mapping: tidy up dma_parms default handling pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode kexec: use file name as the output message prefix fs, seqfile: always allow oom killer seq_file: reuse string_escape_str() fs/seq_file: use seq_* helpers in seq_hex_dump() coredump: change zap_threads() and zap_process() to use for_each_thread() coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMP signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT) signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() signal: turn dequeue_signal_lock() into kernel_dequeue_signal() signals: kill block_all_signals() and unblock_all_signals() nilfs2: fix gcc uninitialized-variable warnings in powerpc build nilfs2: fix gcc unused-but-set-variable warnings MAINTAINERS: nilfs2: add header file for tracing nilfs2: add tracepoints for analyzing reading and writing metadata files ...
| * panic: release stale console lock to always get the logbuf printed outVitaly Kuznetsov2015-11-061-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In some cases we may end up killing the CPU holding the console lock while still having valuable data in logbuf. E.g. I'm observing the following: - A crash is happening on one CPU and console_unlock() is being called on some other. - console_unlock() tries to print out the buffer before releasing the lock and on slow console it takes time. - in the meanwhile crashing CPU does lots of printk()-s with valuable data (which go to the logbuf) and sends IPIs to all other CPUs. - console_unlock() finishes printing previous chunk and enables interrupts before trying to print out the rest, the CPU catches the IPI and never releases console lock. This is not the only possible case: in VT/fb subsystems we have many other console_lock()/console_unlock() users. Non-masked interrupts (or receiving NMI in case of extreme slowness) will have the same result. Getting the whole console buffer printed out on crash should be top priority. [akpm@linux-foundation.org: tweak comment text] Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Baoquan He <bhe@redhat.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Xie XiuQi <xiexiuqi@huawei.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * pidns: fix set/getpriority and ioprio_set/get in PRIO_USER modeBen Segall2015-11-061-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | setpriority(PRIO_USER, 0, x) will change the priority of tasks outside of the current pid namespace. This is in contrast to both the other modes of setpriority and the example of kill(-1). Fix this. getpriority and ioprio have the same failure mode, fix them too. Eric said: : After some more thinking about it this patch sounds justifiable. : : My goal with namespaces is not to build perfect isolation mechanisms : as that can get into ill defined territory, but to build well defined : mechanisms. And to handle the corner cases so you can use only : a single namespace with well defined results. : : In this case you have found the two interfaces I am aware of that : identify processes by uid instead of by pid. Which quite frankly is : weird. Unfortunately the weird unexpected cases are hard to handle : in the usual way. : : I was hoping for a little more information. Changes like this one we : have to be careful of because someone might be depending on the current : behavior. I don't think they are and I do think this make sense as part : of the pid namespace. Signed-off-by: Ben Segall <bsegall@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Ambrose Feinstein <ambrose@google.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * kexec: use file name as the output message prefixMinfei Huang2015-11-063-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kexec output message misses the prefix "kexec", when Dave Young split the kexec code. Now, we use file name as the output message prefix. Currently, the format of output message: [ 140.290795] SYSC_kexec_load: hello, world [ 140.291534] kexec: sanity_check_segment_list: hello, world Ideally, the format of output message: [ 30.791503] kexec: SYSC_kexec_load, Hello, world [ 79.182752] kexec_core: sanity_check_segment_list, Hello, world Remove the custom prefix "kexec" in output message. Signed-off-by: Minfei Huang <mnfhuang@gmail.com> Acked-by: Dave Young <dyoung@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMPOleg Nesterov2015-11-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | task_will_free_mem() is wrong in many ways, and in particular the SIGNAL_GROUP_COREDUMP check is not reliable: a task can participate in the coredumping without SIGNAL_GROUP_COREDUMP bit set. change zap_threads() paths to always set SIGNAL_GROUP_COREDUMP even if other CLONE_VM processes can't react to SIGKILL. Fortunately, at least oom-kill case if fine; it kills all tasks sharing the same mm, so it should also kill the process which actually dumps the core. The change in prepare_signal() is not strictly necessary, it just ensures that the patch does not bring another subtle behavioural change. But it reminds us that this SIGNAL_GROUP_EXIT/COREDUMP case needs more changes. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Kyle Walker <kwalker@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Stanislav Kozina <skozina@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * signals: kill block_all_signals() and unblock_all_signals()Oleg Nesterov2015-11-061-50/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It is hardly possible to enumerate all problems with block_all_signals() and unblock_all_signals(). Just for example, 1. block_all_signals(SIGSTOP/etc) simply can't help if the caller is multithreaded. Another thread can dequeue the signal and force the group stop. 2. Even is the caller is single-threaded, it will "stop" anyway. It will not sleep, but it will spin in kernel space until SIGCONT or SIGKILL. And a lot more. In short, this interface doesn't work at all, at least the last 10+ years. Daniel said: Yeah the only times I played around with the DRM_LOCK stuff was when old drivers accidentally deadlocked - my impression is that the entire DRM_LOCK thing was never really tested properly ;-) Hence I'm all for purging where this leaks out of the drm subsystem. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Dave Airlie <airlied@redhat.com> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * printk: prevent userland from spoofing kernel messagesMathias Krause2015-11-061-5/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following statement of ABI/testing/dev-kmsg is not quite right: It is not possible to inject messages from userspace with the facility number LOG_KERN (0), to make sure that the origin of the messages can always be reliably determined. Userland actually can inject messages with a facility of 0 by abusing the fact that the facility is stored in a u8 data type. By using a facility which is a multiple of 256 the assignment of msg->facility in log_store() implicitly truncates it to 0, i.e. LOG_KERN, allowing users of /dev/kmsg to spoof kernel messages as shown below: The following call... # printf '<%d>Kernel panic - not syncing: beer empty\n' 0 >/dev/kmsg ...leads to the following log entry (dmesg -x | tail -n 1): user :emerg : [ 66.137758] Kernel panic - not syncing: beer empty However, this call... # printf '<%d>Kernel panic - not syncing: beer empty\n' 0x800 >/dev/kmsg ...leads to the slightly different log entry (note the kernel facility): kern :emerg : [ 74.177343] Kernel panic - not syncing: beer empty Fix that by limiting the user provided facility to 8 bit right from the beginning and catch the truncation early. Fixes: 7ff9554bb578 ("printk: convert byte-buffer to variable-length...") Signed-off-by: Mathias Krause <minipli@googlemail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Petr Mladek <pmladek@suse.cz> Cc: Alex Elder <elder@linaro.org> Cc: Joe Perches <joe@perches.com> Cc: Kay Sievers <kay@vrfy.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * module: export param_free_charp()Dan Streetman2015-11-061-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | Change the param_free_charp() function from static to exported. It is used by zswap in the next patch ("zswap: use charp for zswap param strings"). Signed-off-by: Dan Streetman <ddstreet@ieee.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Seth Jennings <sjennings@variantweb.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIMMel Gorman2015-11-061-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __GFP_WAIT was used to signal that the caller was in atomic context and could not sleep. Now it is possible to distinguish between true atomic context and callers that are not willing to sleep. The latter should clear __GFP_DIRECT_RECLAIM so kswapd will still wake. As clearing __GFP_WAIT behaves differently, there is a risk that people will clear the wrong flags. This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly indicate what it does -- setting it allows all reclaim activity, clearing them prevents it. [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm, page_alloc: distinguish between being unable to sleep, unwilling to ↵Mel Gorman2015-11-065-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Merge tag 'trace-v4.4' of ↵Linus Torvalds2015-11-0624-662/+1387
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracking updates from Steven Rostedt: "Most of the changes are clean ups and small fixes. Some of them have stable tags to them. I searched through my INBOX just as the merge window opened and found lots of patches to pull. I ran them through all my tests and they were in linux-next for a few days. Features added this release: ---------------------------- - Module globbing. You can now filter function tracing to several modules. # echo '*:mod:*snd*' > set_ftrace_filter (Dmitry Safonov) - Tracer specific options are now visible even when the tracer is not active. It was rather annoying that you can only see and modify tracer options after enabling the tracer. Now they are in the options/ directory even when the tracer is not active. Although they are still only visible when the tracer is active in the trace_options file. - Trace options are now per instance (although some of the tracer specific options are global) - New tracefs file: set_event_pid. If any pid is added to this file, then all events in the instance will filter out events that are not part of this pid. sched_switch and sched_wakeup events handle next and the wakee pids" * tag 'trace-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (68 commits) tracefs: Fix refcount imbalance in start_creating() tracing: Put back comma for empty fields in boot string parsing tracing: Apply tracer specific options from kernel command line. tracing: Add some documentation about set_event_pid ring_buffer: Remove unneeded smp_wmb() before wakeup of reader benchmark tracing: Allow dumping traces without tracking trace started cpus ring_buffer: Fix more races when terminating the producer in the benchmark ring_buffer: Do no not complete benchmark reader too early tracing: Remove redundant TP_ARGS redefining tracing: Rename max_stack_lock to stack_trace_max_lock tracing: Allow arch-specific stack tracer recordmcount: arm64: Replace the ignored mcount call into nop recordmcount: Fix endianness handling bug for nop_mcount tracepoints: Fix documentation of RCU lockdep checks tracing: ftrace_event_is_function() can return boolean tracing: is_legal_op() can return boolean ring-buffer: rb_event_is_commit() can return boolean ring-buffer: rb_per_cpu_empty() can return boolean ring_buffer: ring_buffer_empty{cpu}() can return boolean ring-buffer: rb_is_reader_page() can return boolean ...
| * tracing: Put back comma for empty fields in boot string parsingSteven Rostedt (Red Hat)2015-11-032-11/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Both early_enable_events() and apply_trace_boot_options() parse a boot string that may get parsed later on. They both use strsep() which converts a comma into a nul character. To still allow the boot string to be parsed again the same way, the nul character gets converted back to a comma after the token is processed. The problem is that these two functions check for an empty parameter (two commas in a row ",,"), and continue the loop if the parameter is empty, but fails to place the comma back. In this case, the second parsing will end at this blank field, and not process fields afterward. In most cases, users should not have an empty field, but if its going to be checked, the code might as well be correct. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Apply tracer specific options from kernel command line.Jiaxing Wang2015-11-031-9/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the trace_options parameter is only applied in tracer_alloc_buffers() when global_trace.current_trace is nop_trace, so a tracer specific option will not be applied even when the specific tracer is also enabled from kernel command line. For example, the 'func_stack_trace' option can't be enabled with the following kernel parameter: ftrace=function ftrace_filter=kfree trace_options=func_stack_trace We can enable tracer specific options by simply apply the options again if the specific tracer is also supplied from command line and started in register_tracer(). To make trace_boot_options_buf can be parsed again, a comma and a space is put back if they were replaced by strsep and strstrip respectively. Also make register_tracer() be __init to access the __init data, and in fact register_tracer is only called from __init code. Link: http://lkml.kernel.org/r/1446599669-9294-1-git-send-email-hello.wjx@gmail.com Signed-off-by: Jiaxing Wang <hello.wjx@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ring_buffer: Remove unneeded smp_wmb() before wakeup of reader benchmarkSteven Rostedt (Red Hat)2015-11-031-2/+0
| | | | | | | | | | | | | | wake_up_process() has a memory barrier before doing anything, thus adding a memory barrier before calling it is redundant. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Allow dumping traces without tracking trace started cpusSasha Levin2015-11-031-2/+3
| | | | | | | | | | | | | | | | | | | | | | We don't init iter->started when dumping the ftrace buffer, and there's no real need to do so - so allow skipping that check if the iter doesn't have an initialized ->started cpumask. Link: http://lkml.kernel.org/r/1441385156-27279-1-git-send-email-sasha.levin@oracle.com Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ring_buffer: Fix more races when terminating the producer in the benchmarkPetr Mladek2015-11-031-25/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The commit b44754d8262d3aab8 ("ring_buffer: Allow to exit the ring buffer benchmark immediately") added a hack into ring_buffer_producer() that set @kill_test when kthread_should_stop() returned true. It improved the situation a lot. It stopped the kthread in most cases because the producer spent most of the time in the patched while cycle. But there are still few possible races when kthread_should_stop() is set outside of the cycle. Then we do not set @kill_test and some other checks pass. This patch adds a better fix. It renames @test_kill/TEST_KILL() into a better descriptive @test_error/TEST_ERROR(). Also it introduces break_test() function that checks for both @test_error and kthread_should_stop(). The new function is used in the producer when the check for @test_error is not enough. It is not used in the consumer because its state is manipulated by the producer via the "reader_finish" variable. Also we add a missing check into ring_buffer_producer_thread() between setting TASK_INTERRUPTIBLE and calling schedule_timeout(). Otherwise, we might miss a wakeup from kthread_stop(). Link: http://lkml.kernel.org/r/1441629518-32712-3-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ring_buffer: Do no not complete benchmark reader too earlyPetr Mladek2015-11-031-9/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It seems that complete(&read_done) might be called too early in some situations. 1st scenario: ------------- CPU0 CPU1 ring_buffer_producer_thread() wake_up_process(consumer); wait_for_completion(&read_start); ring_buffer_consumer_thread() complete(&read_start); ring_buffer_producer() # producing data in # the do-while cycle ring_buffer_consumer(); # reading data # got error # set kill_test = 1; set_current_state( TASK_INTERRUPTIBLE); if (reader_finish) # false schedule(); # producer still in the middle of # do-while cycle if (consumer && !(cnt % wakeup_interval)) wake_up_process(consumer); # spurious wakeup while (!reader_finish && !kill_test) # leaving because # kill_test == 1 reader_finish = 0; complete(&read_done); 1st BANG: We might access uninitialized "read_done" if this is the the first round. # producer finally leaving # the do-while cycle because kill_test == 1; if (consumer) { reader_finish = 1; wake_up_process(consumer); wait_for_completion(&read_done); 2nd BANG: This will never complete because consumer already did the completion. 2nd scenario: ------------- CPU0 CPU1 ring_buffer_producer_thread() wake_up_process(consumer); wait_for_completion(&read_start); ring_buffer_consumer_thread() complete(&read_start); ring_buffer_producer() # CPU3 removes the module <--- difference from # and stops producer <--- the 1st scenario if (kthread_should_stop()) kill_test = 1; ring_buffer_consumer(); while (!reader_finish && !kill_test) # kill_test == 1 => we never go # into the top level while() reader_finish = 0; complete(&read_done); # producer still in the middle of # do-while cycle if (consumer && !(cnt % wakeup_interval)) wake_up_process(consumer); # spurious wakeup while (!reader_finish && !kill_test) # leaving because kill_test == 1 reader_finish = 0; complete(&read_done); BANG: We are in the same "bang" situations as in the 1st scenario. Root of the problem: -------------------- ring_buffer_consumer() must complete "read_done" only when "reader_finish" variable is set. It must not be skipped due to other conditions. Note that we still must keep the check for "reader_finish" in a loop because there might be spurious wakeups as described in the above scenarios. Solution: ---------- The top level cycle in ring_buffer_consumer() will finish only when "reader_finish" is set. The data will be read in "while-do" cycle so that they are not read after an error (kill_test == 1) or a spurious wake up. In addition, "reader_finish" is manipulated by the producer thread. Therefore we add READ_ONCE() to make sure that the fresh value is read in each cycle. Also we add the corresponding barrier to synchronize the sleep check. Next we set the state back to TASK_RUNNING for the situation where we did not sleep. Just from paranoid reasons, we initialize both completions statically. This is safer, in case there are other races that we are unaware of. As a side effect we could remove the memory barrier from ring_buffer_producer_thread(). IMHO, this was the reason for the barrier. ring_buffer_reset() uses spin locks that should provide the needed memory barrier for using the buffer. Link: http://lkml.kernel.org/r/1441629518-32712-2-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Remove redundant TP_ARGS redefiningDmitry Safonov2015-11-031-3/+0
| | | | | | | | | | | | | | | | | | | | TP_ARGS is not used anywhere in trace.h nor trace_entries.h Firstly, I left just #undef TP_ARGS and had no errors - remove it. Link: http://lkml.kernel.org/r/1446576560-14085-1-git-send-email-0x7f454c46@gmail.com Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Rename max_stack_lock to stack_trace_max_lockSteven Rostedt (Red Hat)2015-11-031-8/+8
| | | | | | | | | | | | | | | | Now that max_stack_lock is a global variable, it requires a naming convention that is unlikely to collide. Rename it to the same naming convention that the other stack_trace variables have. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Allow arch-specific stack tracerAKASHI Takahiro2015-11-031-37/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A stack frame may be used in a different way depending on cpu architecture. Thus it is not always appropriate to slurp the stack contents, as current check_stack() does, in order to calcurate a stack index (height) at a given function call. At least not on arm64. In addition, there is a possibility that we will mistakenly detect a stale stack frame which has not been overwritten. This patch makes check_stack() a weak function so as to later implement arch-specific version. Link: http://lkml.kernel.org/r/1446182741-31019-5-git-send-email-takahiro.akashi@linaro.org Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: ftrace_event_is_function() can return booleanYaowei Bai2015-11-022-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | Make ftrace_event_is_function() return bool to improve readability due to this particular function only using either one or zero as its return value. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-9-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: is_legal_op() can return booleanYaowei Bai2015-11-021-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | Make is_legal_op() return bool to improve readability due to this particular function only using either one or zero as its return value. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-8-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ring-buffer: rb_event_is_commit() can return booleanYaowei Bai2015-11-021-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | Make rb_event_is_commit() return bool to improve readability due to this particular function only using either one or zero as its return value. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-7-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ring-buffer: rb_per_cpu_empty() can return booleanYaowei Bai2015-11-021-2/+2
| | | | | | | | | | | | | | | | | | | | | | Makes rb_per_cpu_empty() return bool to improve readability. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-6-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ring_buffer: ring_buffer_empty{cpu}() can return booleanYaowei Bai2015-11-021-5/+5
| | | | | | | | | | | | | | | | | | | | | | Make ring_buffer_empty() and ring_buffer_empty_cpu() return bool. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-5-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ring-buffer: rb_is_reader_page() can return booleanYaowei Bai2015-11-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | Make rb_is_reader_page() return bool to improve readability due to this particular function only using either true or false as its return value. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-4-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: report_latency() in trace_irqsoff.c can return booleanYaowei Bai2015-11-021-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | This patch makes report_latency return bool due to this particular function only using either one or zero as its return value. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-3-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: report_latency() in trace_sched_wakeup.c can return booleanYaowei Bai2015-11-021-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | This patch makes report_latency return bool to improve readability, indicating whether this new latency should be reported/recorded. No functional change. Link: http://lkml.kernel.org/r/1443537816-5788-2-git-send-email-bywxiaobai@163.com Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Update instance_rmdir() to use tracefs_remove_recursiveJiaxing Wang2015-11-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Update instancd_rmdir to use tracefs_remove_recursive instead of debugfs_remove_recursive.This was left in the transition from debugfs to tracefs. Link: http://lkml.kernel.org/r/1445169490-18315-2-git-send-email-hello.wjx@gmail.com Cc: stable@vger.kernel.org # 4.1+ Fixes: 8434dc9340cd2 ("tracing: Convert the tracing facility over to use tracefs") Signed-off-by: Jiaxing Wang <hello.wjx@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Only benchmark the time tracepoints take if tracing is onChunyan Zhang2015-11-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There's no need to record the time tracepoints take when tracing is off. This is because: 1) We cannot see these records since ring_buffer record is off at that moment. 2) If tracing is off and benchmark tracepoint is enabled, the time tracepoint takes is fewer than the same situation when tracing is on, since the tracepoints need to be wrote into ring_buffer, it would take more time. If turn on tracing at this moment, the average and standard deviation cannot exactly present the time that tracepoints take to write data into ring_buffer. Link: http://lkml.kernel.org/r/1445947933-27955-1-git-send-email-zhang.chunyan@linaro.org Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Call on_each_cpu() when adding or removing single pids from ↵Steven Rostedt (Red Hat)2015-11-021-6/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | set_event_pid For the case where pids are already in set_event_pid, and one is added or removed then each CPU should be checked to make sure that the new or old pid is on or not on a CPU. For example: # echo 123 >> set_event_pid or # echo '!123' >> set_event_pid Link: http://lkml.kernel.org/r/20151030061643.GA19480@cac Suggested-by: Jiaxing Wang <hello.wjx@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Fix sparse RCU warningSteven Rostedt (Red Hat)2015-10-261-0/+2
| | | | | | | | | | | | | | | | | | p_start() and p_stop() are seq_file functions that match. Teach sparse to know that rcu_read_lock_sched() that is taken by p_start() is released by p_stop. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Check all tasks on each CPU when filtering pidsSteven Rostedt (Red Hat)2015-10-251-0/+22
| | | | | | | | | | | | | | | | | | | | My tests found that if a task is running but not filtered when set_event_pid is modified, then it can still be traced. Call on_each_cpu() to check if the current running task should be filtered and update the per cpu flags of tr->data appropriately. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Implement event pid filteringSteven Rostedt (Red Hat)2015-10-252-3/+147
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add the necessary hooks to use the pids loaded in set_event_pid to filter all the events enabled in the tracing instance that match the pids listed. Two probes are added to both sched_switch and sched_wakeup tracepoints to be called before other probes are called and after the other probes are called. The first is used to set the necessary flags to let the probes know to test if they should be traced or not. The sched_switch pre probe will set the "ignore_pid" flag if neither the previous or next task has a matching pid. The sched_switch probe will set the "ignore_pid" flag if the next task does not match the matching pid. The pre probe allows for probes tracing sched_switch to be traced if necessary. The sched_wakeup pre probe will set the "ignore_pid" flag if neither the current task nor the wakee task has a matching pid. The sched_wakeup post probe will set the "ignore_pid" flag if the current task does not have a matching pid. Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Add set_event_pid directory for future useSteven Rostedt (Red Hat)2015-10-252-0/+294
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Create a tracing directory called set_event_pid, which currently has no function, but will be used to filter all events for the tracing instance or the pids that are added to the file. The reason no functionality is added with this commit is that this commit focuses on the creation and removal of the pids in a safe manner. And tests can be made against this change to make sure things are correct before hooking features to the list of pids. Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracepoint: Give priority to probes of tracepointsSteven Rostedt (Red Hat)2015-10-251-11/+50
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to guarantee that a probe will be called before other probes that are attached to a tracepoint, there needs to be a mechanism to provide priority of one probe over the others. Adding a prio field to the struct tracepoint_func, which lets the probes be sorted by the priority set in the structure. If no priority is specified, then a priority of 10 is given (this is a macro, and perhaps may be changed in the future). Now probes may be added to affect other probes that are attached to a tracepoint with a guaranteed order. One use case would be to allow tracing of tracepoints be able to filter by pid. A special (higher priority probe) may be added to the sched_switch tracepoint and set the necessary flags of the other tracepoints to notify them if they should be traced or not. In case a tracepoint is enabled at the sched_switch tracepoint too, the order of the two are not random. Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Remove {start,stop}_branch_traceDmitry Safonov2015-10-211-13/+2
| | | | | | | | | | | | | | | | | | | | | | Both start_branch_trace() and stop_branch_trace() are used in only one location, and are both static. As they are small functions there is no need to keep them separated out. Link: http://lkml.kernel.org/r/1445000689-32596-1-git-send-email-0x7f454c46@gmail.com Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: gpio: Add Kconfig option for enabling/disabling trace eventsTal Shorer2015-10-201-0/+7
| | | | | | | | | | | | | | | | | | | | | | Add a new options to trace Kconfig, CONFIG_TRACING_EVENTS_GPIO, that is used for enabling/disabling compilation of gpio function trace events. Link: http://lkml.kernel.org/r/1438432079-11704-4-git-send-email-tal.shorer@gmail.com Acked-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Tal Shorer <tal.shorer@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ftrace: add module globbingDmitry Safonov2015-10-201-15/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Extend module command for function filter selection with globbing. It uses the same globbing as function filter. sh# echo '*alloc*:mod:*' > set_ftrace_filter Will trace any function with the letters 'alloc' in the name in any module but not in kernel. sh# echo '!*alloc*:mod:ipv6' >> set_ftrace_filter Will prevent from tracing functions with 'alloc' in the name from module ipv6 (do not forget to append to set_ftrace_filter file). sh# echo '*alloc*:mod:!ipv6' > set_ftrace_filter Will trace functions with 'alloc' in the name from kernel and any module except ipv6. sh# echo '*alloc*:mod:!*' > set_ftrace_filter Will trace any function with the letters 'alloc' in the name only from kernel, but not from any module. sh# echo '*:mod:!*' > set_ftrace_filter or sh# echo ':mod:!' > set_ftrace_filter Will trace every function in the kernel, but will not trace functions from any module. sh# echo '*:mod:*' > set_ftrace_filter or sh# echo ':mod:' > set_ftrace_filter As the opposite will trace all functions from all modules, but not from kernel. sh# echo '*:mod:*snd*' > set_ftrace_filter Will trace your sound drivers only (if any). Link: http://lkml.kernel.org/r/1443545176-3215-4-git-send-email-0x7f454c46@gmail.com Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com> [ Made format changes ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ftrace: Introduce ftrace_glob structureDmitry Safonov2015-10-201-38/+46
| | | | | | | | | | | | | | | | | | | | | | | | | | ftrace_match parameters are very related and I reduce the number of local variables & parameters with it. This is also preparation for module globbing as it would introduce more realated variables & parameters. Link: http://lkml.kernel.org/r/1443545176-3215-3-git-send-email-0x7f454c46@gmail.com Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com> [ Made some formatting changes ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ftrace: Clarify code for mod commandDmitry Safonov2015-10-161-27/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | "Not" is too abstract variable name - changed to clear_filter. Removed ftrace_match_module_records function: comparison with !* or * not does the general code in filter_parse_regex() as it works without mod command for sh# echo '!*' > /sys/kernel/debug/tracing/set_ftrace_filter Link: http://lkml.kernel.org/r/1443545176-3215-2-git-send-email-0x7f454c46@gmail.com Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ftrace: Remove redundant strsep in mod_callbackDmitry Safonov2015-10-131-10/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | By now there isn't any subcommand for mod. Before: sh$ echo '*:mod:ipv6:a' > set_ftrace_filter sh$ echo '*:mod:ipv6' > set_ftrace_filter had the same results, but now first will result in: sh$ echo '*:mod:ipv6:a' > set_ftrace_filter -bash: echo: write error: Invalid argument Also, I clarified ftrace_mod_callback code a little. Link: http://lkml.kernel.org/r/1443545176-3215-1-git-send-email-0x7f454c46@gmail.com Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com> [ converted 'if (ret == 0)' to 'if (!ret)' ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * ftrace: Remove redundant swap functionRasmus Villemoes2015-10-011-12/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | To cover the common case of sorting an array of pointers, Daniel Wagner recently modified the library sort() to use a specific swap function for size==8, in addition to the size==4 case which was already handled. Since sizeof(long) is either 4 or 8, ftrace_swap_ips() is redundant and we can just let sort() pick an appropriate and fast swap callback. Link: http://lkml.kernel.org/r/1441834023-13130-1-git-send-email-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Use kstrdup_const instead of private implementationRasmus Villemoes2015-10-011-16/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kernel now has kstrdup_const/kfree_const for reusing .rodata (typically string literals) when possible; there's no reason to duplicate that logic in the tracing system. Moreover, as the comment above core_kernel_data states, it may not always return true for .rodata - that is for example the case on x86_64, where we thus end up kstrdup'ing all the passed-in strings. Arguably, testing for .rodata explicitly (as kstrdup_const does) is also more correct: I don't think one is supposed to be able to change the name after creating the event_subsystem by passing the address of a static char (but non-const) array. Link: http://lkml.kernel.org/r/1441833841-12955-1-git-send-email-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Add trace options for tracer options to instancesSteven Rostedt (Red Hat)2015-09-302-22/+67
| | | | | | | | | | | | | | | | | | Add the tracer options to instances options directory as well. Only add the options for tracers that are allowed to be enabled by an instance. But note, that tracer options are global. That is, tracer options enabled in an instance, also take affect at the top level and in other instances. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Add trace options for core options to instancesSteven Rostedt (Red Hat)2015-09-301-5/+14
| | | | | | | | | | | | | | | | | | Allow instances to have their own options, at least for the core options (non tracer specific ones). There are a few global options that should not be added to instances, like enabling of trace_printk, and the sched comm recording, which do not have a specific trace instance associated to them. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Make ftrace_trace_stack() depend on general trace_array flagSteven Rostedt (Red Hat)2015-09-302-13/+16
| | | | | | | | | | | | | | | | In preparation for the multi buffer instances to have their own trace_flags, the check in ftrace_trace_stack() needs to test the trace_array descriptor flag that is for the current event, not the global_trace descriptor. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Add a method to pass in trace_array descriptor to option filesSteven Rostedt (Red Hat)2015-09-302-7/+63
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In preparation of having the multi buffer instances having their own trace option flags, the trace option files needs a way to not only pass in the flag they represent, but also the trace_array descriptor. A new field is added to the trace_array descriptor called trace_flags_index, which is a 32 byte character array representing a bit. This array is simply filled with the index of the array, where index_array[n] = n; Then the address of this array is passed to the file callbacks instead of the index of the flag index. Then to retrieve both the flag index and the trace_array descriptor: data is the passed in argument. index = *(unsigned char *)data; data -= index; /* Now data points to the address of the array in the trace_array */ tr = container_of(data, struct trace_array, trace_flags_index); Suggested-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * tracing: Move trace_flags from global to a trace_array fieldSteven Rostedt (Red Hat)2015-09-3010-101/+135
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In preparation to make trace options per instance, the global trace_flags needs to be moved from being a global variable to a field within the trace instance trace_array structure. There's still more work to do, as there's some functions that use trace_flags without passing in a way to get to the current_trace array. For those, the global_trace is used directly (from trace.c). This includes setting and clearing the trace_flags. This means that when a new instance is created, it just gets the trace_flags of the global_trace and will not be able to modify them. Depending on the functions that have access to the trace_array, the flags of an instance may not affect parts of its trace, where the global_trace is used. These will be fixed in future changes. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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