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* tracing: Only run synchronize_sched() at instance deletion timeSteven Rostedt2013-12-051-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It has been reported that boot up with FTRACE_SELFTEST enabled can take a very long time. There can be stalls of over a minute. This was tracked down to the synchronize_sched() called when a system call event is disabled. As the self tests enable and disable thousands of events, this makes the synchronize_sched() get called thousands of times. The synchornize_sched() was added with d562aff93bfb53 "tracing: Add support for SOFT_DISABLE to syscall events" which caused this regression (added in 3.13-rc1). The synchronize_sched() is to protect against the events being accessed when a tracer instance is being deleted. When an instance is being deleted all the events associated to it are unregistered. The synchronize_sched() makes sure that no more users are running when it finishes. Instead of calling synchronize_sched() for all syscall events, we only need to call it once, after the events are unregistered and before the instance is deleted. The event_mutex is held during this action to prevent new users from enabling events. Link: http://lkml.kernel.org/r/20131203124120.427b9661@gandalf.local.home Reported-by: Petr Mladek <pmladek@suse.cz> Acked-by: Tom Zanussi <tom.zanussi@linux.intel.com> Acked-by: Petr Mladek <pmladek@suse.cz> Tested-by: Petr Mladek <pmladek@suse.cz> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Do not assign filp->private_data to freed memoryGeyslan G. Bem2013-11-061-1/+8
| | | | | | | | | | | | | | | | | In system_tr_open(), the filp->private_data can be assigned the 'dir' variable even if it was freed. This is on the error path, and is harmless because the error return code will prevent filp->private_data from being used. But for correctness, we should not assign it to a recently freed variable, as that can cause static tools to give false warnings. Also have both subsystem_open() and system_tr_open() return -ENODEV if tracing has been disabled. Link: http://lkml.kernel.org/r/1383764571-7318-1-git-send-email-geyslan@gmail.com Signed-off-by: Geyslan G. Bem <geyslan@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Update event filters for multibufferTom Zanussi2013-11-051-11/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The trace event filters are still tied to event calls rather than event files, which means you don't get what you'd expect when using filters in the multibuffer case: Before: # echo 'bytes_alloc > 8192' > /sys/kernel/debug/tracing/events/kmem/kmalloc/filter # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter bytes_alloc > 8192 # mkdir /sys/kernel/debug/tracing/instances/test1 # echo 'bytes_alloc > 2048' > /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter bytes_alloc > 2048 # cat /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter bytes_alloc > 2048 Setting the filter in tracing/instances/test1/events shouldn't affect the same event in tracing/events as it does above. After: # echo 'bytes_alloc > 8192' > /sys/kernel/debug/tracing/events/kmem/kmalloc/filter # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter bytes_alloc > 8192 # mkdir /sys/kernel/debug/tracing/instances/test1 # echo 'bytes_alloc > 2048' > /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter bytes_alloc > 8192 # cat /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter bytes_alloc > 2048 We'd like to just move the filter directly from ftrace_event_call to ftrace_event_file, but there are a couple cases that don't yet have multibuffer support and therefore have to continue using the current event_call-based filters. For those cases, a new USE_CALL_FILTER bit is added to the event_call flags, whose main purpose is to keep the old behavior for those cases until they can be updated with multibuffer support; at that point, the USE_CALL_FILTER flag (and the new associated call_filter_check_discard() function) can go away. The multibuffer support also made filter_current_check_discard() redundant, so this change removes that function as well and replaces it with filter_check_discard() (or call_filter_check_discard() as appropriate). Link: http://lkml.kernel.org/r/f16e9ce4270c62f46b2e966119225e1c3cca7e60.1382620672.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Kill the !CONFIG_MODULES code in trace_events.cOleg Nesterov2013-08-211-12/+6
| | | | | | | | | | | | | Move trace_module_nb under CONFIG_MODULES and kill the dummy trace_module_notify(). Imho it doesn't make sense to define "struct notifier_block" and its .notifier_call just to avoid "ifdef" in event_trace_init(), and all other !CONFIG_MODULES code has already gone away. Link: http://lkml.kernel.org/r/20130731173137.GA31043@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Don't pass file_operations array to event_create_dir()Oleg Nesterov2013-08-211-34/+12
| | | | | | | | | | | Now that event_create_dir() and __trace_add_new_event() always use the same file_operations we can kill these arguments and simplify the code. Link: http://lkml.kernel.org/r/20130731173135.GA31040@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Kill trace_create_file_ops() and friendsOleg Nesterov2013-08-211-144/+9
| | | | | | | | | | | | | | | | | trace_create_file_ops() allocates the copy of id/filter/format/enable file_operations to set "f_op->owner = mod" for fops_get(). However after the recent changes there is no reason to prevent rmmod even if one of these files is opened. A file operation can do nothing but fail after remove_event_file_dir() clears ->i_private for every file removed by trace_module_remove_events(). Kill "struct ftrace_module_file_ops" and fix the compilation errors. Link: http://lkml.kernel.org/r/20130731173132.GA31033@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Add comment to describe special break case in probe_remove_event_call()Steven Rostedt (Red Hat)2013-07-311-0/+6
| | | | | | | | | | | | | The "break" used in the do_for_each_event_file() is used as an optimization as the loop is really a double loop. The loop searches all event files for each trace_array. There's only one matching event file per trace_array and after we find the event file for the trace_array, the break is used to jump to the next trace_array and start the search there. As this is not a standard way of using "break" in C code, it requires a comment right before the break to let people know what is going on. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: trace_remove_event_call() should fail if call/file is in useOleg Nesterov2013-07-311-2/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | Change trace_remove_event_call(call) to return the error if this call is active. This is what the callers assume but can't verify outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c need the additional changes, unregister_trace_probe() should abort if trace_remove_event_call() fails. The caller is going to free this call/file so we must ensure that nobody can use them after trace_remove_event_call() succeeds. debugfs should be fine after the previous changes and event_remove() does TRACE_REG_UNREGISTER, but still there are 2 reasons why we need the additional checks: - There could be a perf_event(s) attached to this tp_event, so the patch checks ->perf_refcount. - TRACE_REG_UNREGISTER can be suppressed by FTRACE_EVENT_FL_SOFT_MODE, so we simply check FTRACE_EVENT_FL_ENABLED protected by event_mutex. Link: http://lkml.kernel.org/r/20130729175033.GB26284@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_privateOleg Nesterov2013-07-291-32/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Change remove_event_file_dir() to clear ->i_private for every file we are going to remove. We need to check file->dir != NULL because event_create_dir() can fail. debugfs_remove_recursive(NULL) is fine but the patch moves it under the same check anyway for readability. spin_lock(d_lock) and "d_inode != NULL" check are not needed afaics, but I do not understand this code enough. tracing_open_generic_file() and tracing_release_generic_file() can go away, ftrace_enable_fops and ftrace_event_filter_fops() use tracing_open_generic() but only to check tracing_disabled. This fixes all races with event_remove() or instance_delete(). f_op->read/write/whatever can never use the freed file/call, all event/* files were changed to check and use ->i_private under event_mutex. Note: this doesn't not fix other problems, event_remove() can destroy the active ftrace_event_call, we need more changes but those changes are completely orthogonal. Link: http://lkml.kernel.org/r/20130728183527.GB16723@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Introduce remove_event_file_dir()Oleg Nesterov2013-07-291-24/+23
| | | | | | | | | | | | | | | Preparation for the next patch. Extract the common code from remove_event_from_tracers() and __trace_remove_event_dirs() into the new helper, remove_event_file_dir(). The patch looks more complicated than it actually is, it also moves remove_subsystem() up to avoid the forward declaration. Link: http://lkml.kernel.org/r/20130726172547.GA3629@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Change f_start() to take event_mutex and verify i_private != NULLOleg Nesterov2013-07-291-4/+9
| | | | | | | | | | | | | | | | | | | | trace_format_open() and trace_format_seq_ops are racy, nothing protects ftrace_event_call from trace_remove_event_call(). Change f_start() to take event_mutex and verify i_private != NULL, change f_stop() to drop this lock. This fixes nothing, but now we can change debugfs_remove("format") callers to nullify ->i_private and fix the the problem. Note: the usage of event_mutex is sub-optimal but simple, we can change this later. Link: http://lkml.kernel.org/r/20130726172543.GA3622@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Change event_filter_read/write to verify i_private != NULLOleg Nesterov2013-07-291-7/+19
| | | | | | | | | | | | | | | | | | | | event_filter_read/write() are racy, ftrace_event_call can be already freed by trace_remove_event_call() callers. 1. Shift mutex_lock(event_mutex) from print/apply_event_filter to the callers. 2. Change the callers, event_filter_read() and event_filter_write() to read i_private under this mutex and abort if it is NULL. This fixes nothing, but now we can change debugfs_remove("filter") callers to nullify ->i_private and fix the the problem. Link: http://lkml.kernel.org/r/20130726172540.GA3619@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Change event_enable/disable_read() to verify i_private != NULLOleg Nesterov2013-07-291-10/+20
| | | | | | | | | | | | | | | | | tracing_open_generic_file() is racy, ftrace_event_file can be already freed by rmdir or trace_remove_event_call(). Change event_enable_read() and event_disable_read() to read and verify "file = i_private" under event_mutex. This fixes nothing, but now we can change debugfs_remove("enable") callers to nullify ->i_private and fix the the problem. Link: http://lkml.kernel.org/r/20130726172536.GA3612@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Turn event/id->i_private into call->event.typeOleg Nesterov2013-07-291-5/+13
| | | | | | | | | | | | | | | | | | | | | event_id_read() is racy, ftrace_event_call can be already freed by trace_remove_event_call() callers. Change event_create_dir() to pass "data = call->event.type", this is all event_id_read() needs. ftrace_event_id_fops no longer needs tracing_open_generic(). We add the new helper, event_file_data(), to read ->i_private, it will have more users. Note: currently ACCESS_ONCE() and "id != 0" check are not needed, but we are going to change event_remove/rmdir to clear ->i_private. Link: http://lkml.kernel.org/r/20130726172532.GA3605@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Do not (ab)use trace_seq in event_id_read()Oleg Nesterov2013-07-181-13/+4
| | | | | | | | | | | | | | | | | | event_id_read() has no reason to kmalloc "struct trace_seq" (more than PAGE_SIZE!), it can use a small buffer instead. Note: "if (*ppos) return 0" looks strange and even wrong, simple_read_from_buffer() handles ppos != 0 case corrrectly. And it seems that almost every user of trace_seq in this file should be converted too. Unless you use seq_open(), trace_seq buys nothing compared to the raw buffer, but it needs a bit more memory and code. Link: http://lkml.kernel.org/r/20130718184712.GA4786@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Simplify the iteration logic in f_start/f_nextOleg Nesterov2013-07-181-38/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | f_next() looks overcomplicated, and it is not strictly correct even if this doesn't matter. Say, FORMAT_FIELD_SEPERATOR should not return NULL (means EOF) if trace_get_fields() returns an empty list, we should simply advance to FORMAT_PRINTFMT as we do when we find the end of list. 1. Change f_next() to return "struct list_head *" rather than "ftrace_event_field *", and change f_show() to do list_entry(). This simplifies the code a bit, only f_show() needs to know about ftrace_event_field, and f_next() can play with ->prev directly 2. Change f_next() to not play with ->prev / return inside the switch() statement. It can simply set node = head/common_head, the prev-or-advance-to-the-next-magic below does all work. While at it. f_start() looks overcomplicated too. I don't think *pos == 0 makes sense as a separate case, just change this code to do "while" instead of "do/while". The patch also moves f_start() down, close to f_stop(). This is purely cosmetic, just to make the locking added by the next patch more clear/visible. Link: http://lkml.kernel.org/r/20130718184710.GA4783@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Miscellaneous fixes for trace_array ref countingAlexander Z Lam2013-07-181-2/+19
| | | | | | | | | | | | | | Some error paths did not handle ref counting properly, and some trace files need ref counting. Link: http://lkml.kernel.org/r/1374171524-11948-1-git-send-email-azl@google.com Cc: stable@vger.kernel.org # 3.10 Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: David Sharp <dhsharp@google.com> Cc: Alexander Z Lam <lambchop468@gmail.com> Signed-off-by: Alexander Z Lam <azl@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Fix race between deleting buffer and setting eventsSteven Rostedt (Red Hat)2013-07-021-6/+17
| | | | | | | | | | | | | | While analyzing the code, I discovered that there's a potential race between deleting a trace instance and setting events. There are a few races that can occur if events are being traced as the buffer is being deleted. Mostly the problem comes with freeing the descriptor used by the trace event callback. To prevent problems like this, the events are disabled before the buffer is deleted. The problem with the current solution is that the event_mutex is let go between disabling the events and freeing the files, which means that the events could be enabled again while the freeing takes place. Cc: stable@vger.kernel.org # 3.10 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Add trace_array_get/put() to event handlingSteven Rostedt (Red Hat)2013-07-021-4/+51
| | | | | | | | | | | | | | | | | | | | | | | | | | Commit a695cb58162 "tracing: Prevent deleting instances when they are being read" tried to fix a race between deleting a trace instance and reading contents of a trace file. But it wasn't good enough. The following could crash the kernel: # cd /sys/kernel/debug/tracing/instances # ( while :; do mkdir foo; rmdir foo; done ) & # ( while :; do echo 1 > foo/events/sched/sched_switch 2> /dev/null; done ) & Luckily this can only be done by root user, but it should be fixed regardless. The problem is that a delete of the file can happen after the write to the event is opened, but before the enabling happens. The solution is to make sure the trace_array is available before succeeding in opening for write, and incerment the ref counter while opened. Now the instance can be deleted when the events are writing to the buffer, but the deletion of the instance will disable all events before the instance is actually deleted. Cc: stable@vger.kernel.org # 3.10 Reported-by: Alexander Lam <azl@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Protect ftrace_trace_arrays list in trace_events.cAlexander Z Lam2013-07-011-1/+10
| | | | | | | | | | | | | | There are multiple places where the ftrace_trace_arrays list is accessed in trace_events.c without the trace_types_lock held. Link: http://lkml.kernel.org/r/1372732674-22726-1-git-send-email-azl@google.com Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: David Sharp <dhsharp@google.com> Cc: Alexander Z Lam <lambchop468@gmail.com> Cc: stable@vger.kernel.org # 3.10 Signed-off-by: Alexander Z Lam <azl@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Fix disabling of soft disableTom Zanussi2013-07-011-1/+3
| | | | | | | | | | | | | | | | | | | | | The comment on the soft disable 'disable' case of __ftrace_event_enable_disable() states that the soft disable bit should be cleared in that case, but currently only the soft mode bit is actually cleared. This essentially leaves the standard non-soft-enable enable/disable paths as the only way to clear the soft disable flag, but the soft disable bit should also be cleared when removing a trigger with '!'. Also, the SOFT_DISABLED bit should never be set if SOFT_MODE is cleared. This fixes the above discrepancies. Link: http://lkml.kernel.org/r/b9c68dd50bc07019e6c67d3f9b29be4ef1b2badb.1372479499.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Simplify code for showing of soft disabled flagTom Zanussi2013-07-011-10/+10
| | | | | | | | | | | Rather than enumerating each permutation, build the enable state string up from the combination of states. This also allows for the simpler addition of more states. Link: http://lkml.kernel.org/r/9aff5af6dee2f5a40ca30df41c39d5f33e998d7a.1372479499.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Failed to create system directorySteven Rostedt2013-07-011-6/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Running the following: # cd /sys/kernel/debug/tracing # echo p:i do_sys_open > kprobe_events # echo p:j schedule >> kprobe_events # cat kprobe_events p:kprobes/i do_sys_open p:kprobes/j schedule # echo p:i do_sys_open >> kprobe_events # cat kprobe_events p:kprobes/j schedule p:kprobes/i do_sys_open # ls /sys/kernel/debug/tracing/events/kprobes/ enable filter j Notice that the 'i' is missing from the kprobes directory. The console produces: "Failed to create system directory kprobes" This is because kprobes passes in a allocated name for the system and the ftrace event subsystem saves off that name instead of creating a duplicate for it. But the kprobes may free the system name making the pointer to it invalid. This bug was introduced by 92edca073c37 "tracing: Use direct field, type and system names" which switched from using kstrdup() on the system name in favor of just keeping apointer to it, as the internal ftrace event system names are static and exist for the life of the computer being booted. Instead of reverting back to duplicating system names again, we can use core_kernel_data() to determine if the passed in name was allocated or static. Then use the MSB of the ref_count to be a flag to keep track if the name was allocated or not. Then we can still save from having to duplicate strings that will always exist, but still copy the ones that may be freed. Cc: stable@vger.kernel.org # 3.10 Reported-by: "zhangwei(Jovi)" <jovi.zhangwei@huawei.com> Reported-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Do not call kmem_cache_free() on allocation failureNamhyung Kim2013-06-111-6/+1
| | | | | | | | | There's no point calling it when _alloc() failed. Link: http://lkml.kernel.org/r/1370585268-29169-1-git-send-email-namhyung@kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing/trivial: Consolidate error return conditionHarsh Prateek Bora2013-06-111-4/+1
| | | | | | | | | | Consolidate the checks for !enabled and !param to return -EINVAL in event_enable_func(). Link: http://lkml.kernel.org/r/1369380137-12452-1-git-send-email-harsh@linux.vnet.ibm.com Signed-off-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Return -EBUSY when event_enable_func() fails to get moduleMasami Hiramatsu2013-05-161-1/+3
| | | | | | | | | | | | | | | | | | | | Since try_module_get() returns false( = 0) when it fails to pindown a module, event_enable_func() returns 0 which means "succeed". This can cause a kernel panic when the entry is removed, because the event is already released. This fixes the bug by returning -EBUSY, because the reason why it fails is that the module is being removed at that time. Link: http://lkml.kernel.org/r/20130516114848.13508.97899.stgit@mhiramat-M0-7522 Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tom Zanussi <tom.zanussi@intel.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Add helper function trace_create_new_event() to remove duplicate codeSteven Rostedt (Red Hat)2013-05-091-12/+20
| | | | | | | | | | | | | | Both __trace_add_new_event() and __trace_early_add_new_event() do basically the same thing, except that __trace_add_new_event() does a little more. Instead of having duplicate code between the two functions, add a helper function trace_create_new_event() that both can use. This will help against having bugs fixed in one function but not the other. Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Modify soft-mode only if there's no other referrerMasami Hiramatsu2013-05-091-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Modify soft-mode flag only if no other soft-mode referrer (currently only the ftrace triggers) by using a reference counter in each ftrace_event_file. Without this fix, adding and removing several different enable/disable_event triggers on the same event clear soft-mode bit from the ftrace_event_file. This also happens with a typo of glob on setting triggers. e.g. # echo vfs_symlink:enable_event:net:netif_rx > set_ftrace_filter # cat events/net/netif_rx/enable 0* # echo typo_func:enable_event:net:netif_rx > set_ftrace_filter # cat events/net/netif_rx/enable 0 # cat set_ftrace_filter #### all functions enabled #### vfs_symlink:enable_event:net:netif_rx:unlimited As above, we still have a trigger, but soft-mode is gone. Link: http://lkml.kernel.org/r/20130509054429.30398.7464.stgit@mhiramat-M0-7522 Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: David Sharp <dhsharp@google.com> Cc: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com> Cc: Tom Zanussi <tom.zanussi@intel.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Indicate enabled soft-mode in enable fileMasami Hiramatsu2013-05-091-0/+2
| | | | | | | | | | | | | | | | Indicate enabled soft-mode event as "1*" in "enable" file for each event, because it can be soft-disabled when disable_event trigger is hit. Link: http://lkml.kernel.org/r/20130509054426.30398.28202.stgit@mhiramat-M0-7522 Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Tom Zanussi <tom.zanussi@intel.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Return error if register_ftrace_function_probe() fails for ↵Steven Rostedt (Red Hat)2013-05-091-2/+9
| | | | | | | | | | | | | | | | | event_enable_func() register_ftrace_function_probe() returns the number of functions it registered, which can be zero, it can also return a negative number if something went wrong. But event_enable_func() only checks for the case that it didn't register anything, it needs to also check for the case that something went wrong and return that error code as well. Added some comments about the code as well, to make it more understandable. Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Don't succeed if event_enable_func did not register anythingMasami Hiramatsu2013-05-091-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | Return 0 instead of the number of activated ftrace function probes if event_enable_func succeeded and return an error code if it failed or did not register any functions. But it currently returns the number of registered functions and if it didn't register anything, it returns 0, but that is considered success. This also fixes the return value. As if it succeeds, it returns the number of functions that were enabled, which is returned back to the user in ftrace_regex_write (the write() return code). If only one function is enabled, then the return code of the write is one, and this can confuse the user program in thinking it only wrote 1 byte. Link: http://lkml.kernel.org/r/20130509054413.30398.55650.stgit@mhiramat-M0-7522 Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Tom Zanussi <tom.zanussi@intel.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> [ Rewrote change log to reflect that this fixes two bugs - SR ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Rename trace_event_mutex to trace_event_semzhangwei(Jovi)2013-03-151-11/+11
| | | | | | | | | | trace_event_mutex is an rw semaphore now, not a mutex, change the name. Link: http://lkml.kernel.org/r/513D843B.40109@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> [ Forward ported to my new code ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Convert trace_destroy_fields() to staticzhangwei(Jovi)2013-03-151-1/+1
| | | | | | | | | | trace_destroy_fields() is not used outside of the file. It can be a static function. Link: http://lkml.kernel.org/r/513D842A.2000907@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Move find_event_field() into trace_events.czhangwei(Jovi)2013-03-151-2/+29
| | | | | | | | | | | | | | | By moving find_event_field() and trace_find_field() into trace_events.c, the ftrace_common_fields list and trace_get_fields() can become local to the trace_events.c file. find_event_field() is renamed to trace_find_event_field() to conform to the tracing global function names. Link: http://lkml.kernel.org/r/513D8426.9070109@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> [ rostedt: Modified trace_find_field() to trace_find_event_field() ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Add function probe triggers to enable/disable eventsSteven Rostedt (Red Hat)2013-03-151-0/+279
| | | | | | | | | | | | | | | | | | | | | | | | | | Add triggers to function tracer that lets an event get enabled or disabled when a function is called: format is: <function>:enable_event:<system>:<event>[:<count>] <function>:disable_event:<system>:<event>[:<count>] echo 'schedule:enable_event:sched:sched_switch' > /debug/tracing/set_ftrace_filter Every time schedule is called, it will enable the sched_switch event. echo 'schedule:disable_event:sched:sched_switch:2' > /debug/tracing/set_ftrace_filter The first two times schedule is called while the sched_switch event is enabled, it will disable it. It will not count for a time that the event is already disabled (or enabled for enable_event). [ fixed return without mutex_unlock() - thanks to Dan Carpenter and smatch ] Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Add a way to soft disable trace eventsSteven Rostedt (Red Hat)2013-03-151-13/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to let triggers enable or disable events, we need a 'soft' method for doing so. For example, if a function probe is added that lets a user enable or disable events when a function is called, that change must be done without taking locks or a mutex, and definitely it can't sleep. But the full enabling of a tracepoint is expensive. By adding a 'SOFT_DISABLE' flag, and converting the flags to be updated without the protection of a mutex (using set/clear_bit()), this soft disable flag can be used to allow critical sections to enable or disable events from being traced (after the event has been placed into "SOFT_MODE"). Some caveats though: The comm recorder (to map pids with a comm) can not be soft disabled (yet). If you disable an event with with a "soft" disable and wait a while before reading the trace, the comm cache may be replaced and you'll get a bunch of <...> for comms in the trace. Reading the "enable" file for an event that is disabled will now give you "0*" where the '*' denotes that the tracepoint is still active but the event itself is "disabled". [ fixed _BIT used in & operation : thanks to Dan Carpenter and smatch ] Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Add alloc_snapshot kernel command line parameterSteven Rostedt (Red Hat)2013-03-151-2/+2
| | | | | | | | | | | | | | | | | | | If debugging the kernel, and the developer wants to use tracing_snapshot() in places where tracing_snapshot_alloc() may be difficult (or more likely, the developer is lazy and doesn't want to bother with tracing_snapshot_alloc() at all), then adding alloc_snapshot to the kernel command line parameter will tell ftrace to allocate the snapshot buffer (if configured) when it allocates the main tracing buffer. I also noticed that ring_buffer_expanded and tracing_selftest_disabled had inconsistent use of boolean "true" and "false" with "0" and "1". I cleaned that up too. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Clear all trace buffers when unloaded module event was usedSteven Rostedt (Red Hat)2013-03-151-3/+7
| | | | | | | | | | | | Currently we do not know what buffer a module event was enabled in. On unload, it is safest to clear all buffer instances, not just the top level buffer. Todo: Clear only the buffer that the event was used in. The infrastructure is there to do this, but it makes the code a bit more complex. Lets get the current code vetted before we add that. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Only clear trace buffer on module unload if event was tracedSteven Rostedt (Red Hat)2013-03-151-4/+8
| | | | | | | | | | | | | | Currently, when a module with events is unloaded, the trace buffer is cleared. This is just a safety net in case the module might have some strange callback when its event is outputted. But there's no reason to reset the buffer if the module didn't have any of its events traced. Add a flag to the event "call" structure called WAS_ENABLED and gets set when the event is ever enabled, and this flag never gets cleared. When a module gets unloaded, if any of its events have this flag set, then the trace buffer will get cleared. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Fix trace events build without modulesSteven Rostedt (Red Hat)2013-03-151-19/+36
| | | | | | | | | | | | | | | | | The new multi-buffers added a descriptor that kept track of module events, and the directories they use, with struct ftace_module_file_ops. This is used to add a ref count to keep modules from unloading while their files are being accessed. As the descriptor is only needed when CONFIG_MODULES is enabled, it is only declared when the config is enabled. But that struct is dereferenced in a few areas outside the #ifdef CONFIG_MODULES. By adding some helper routines and moving code around a little, events can be compiled again without modules. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Use direct field, type and system namesSteven Rostedt2013-03-151-17/+3
| | | | | | | | | | | | | The names used to display the field and type in the event format files are copied, as well as the system name that is displayed. All these names are created by constant values passed in. If one of theses values were to be removed by a module, the module would also be required to remove any event it created. By using the strings directly, we can save over 100K of memory. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Use kmem_cache_alloc instead of kmalloc in trace_events.cSteven Rostedt2013-03-151-7/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The event structures used by the trace events are mostly persistent, but they are also allocated by kmalloc, which is not the best at allocating space for what is used. By converting these kmallocs into kmem_cache_allocs, we can save over 50K of space that is permanently allocated. After boot we have: slab name active allocated size --------- ------ --------- ---- ftrace_event_file 979 1005 56 67 1 ftrace_event_field 2301 2310 48 77 1 The ftrace_event_file has at boot up 979 active objects out of 1005 allocated in the slabs. Each object is 56 bytes. In a normal kmalloc, that would allocate 64 bytes for each object. 1005 - 979 = 26 objects not used 26 * 56 = 1456 bytes wasted But if we used kmalloc: 64 - 56 = 8 bytes unused per allocation 8 * 979 = 7832 bytes wasted 7832 - 1456 = 6376 bytes in savings Doing the same for ftrace_event_field where there's 2301 objects allocated in a slab that can hold 2310 with 48 bytes each we have: 2310 - 2301 = 9 objects not used 9 * 48 = 432 bytes wasted A kmalloc would also use 64 bytes per object: 64 - 48 = 16 bytes unused per allocation 16 * 2301 = 36816 bytes wasted! 36816 - 432 = 36384 bytes in savings This change gives us a total of 42760 bytes in savings. At least on my machine, but as there's a lot of these persistent objects for all configurations that use trace points, this is a net win. Thanks to Ezequiel Garcia for his trace_analyze presentation which pointed out the wasted space in my code. Cc: Ezequiel Garcia <elezegarcia@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Get trace_events kernel command line working againSteven Rostedt2013-03-151-7/+136
| | | | | | | | | | | | | | | | | | | | | | With the new descriptors used to allow multiple buffers in the tracing directory added, the kernel command line parameter trace_events=... no longer works. This is because the top level (global) trace array now has a list of descriptors associated with the events and the files in the debugfs directory. But in early bootup, when the command line is processed and the events enabled, the trace array list of events has not been set up yet. Without the list of events in the trace array, the setting of events to record will fail because it would not match any events. The solution is to set up the top level array in two stages. The first is to just add the ftrace file descriptors that just point to the events. This will allow events to be enabled and start tracing. The second stage is called after the filesystem is set up, and this stage will create the debugfs event files and directories associated with the trace array events. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Add rmdir to remove multibuffer instancesSteven Rostedt2013-03-151-0/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | Add a method to the hijacked dentry descriptor of the "instances" directory to allow for rmdir to remove an instance of a multibuffer. Example: cd /debug/tracing/instances mkdir hello ls hello/ rmdir hello ls Like the mkdir method, the i_mutex is dropped for the instances directory. The instances directory is created at boot up and can not be renamed or removed. The trace_types_lock mutex is used to synchronize adding and removing of instances. I've run several stress tests with different threads trying to create and delete directories of the same name, and it has stood up fine. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Add interface to allow multiple trace buffersSteven Rostedt2013-03-151-1/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add the interface ("instances" directory) to add multiple buffers to ftrace. To create a new instance, simply do a mkdir in the instances directory: This will create a directory with the following: # cd instances # mkdir foo # ls foo buffer_size_kb free_buffer trace_clock trace_pipe buffer_total_size_kb set_event trace_marker tracing_enabled events/ trace trace_options tracing_on Currently only events are able to be set, and there isn't a way to delete a buffer when one is created (yet). Note, the i_mutex lock is dropped from the parent "instances" directory during the mkdir operation. As the "instances" directory can not be renamed or deleted (created on boot), I do not see any harm in dropping the lock. The creation of the sub directories is protected by trace_types_lock mutex, which only lets one instance get into the code path at a time. If two tasks try to create or delete directories of the same name, only one will occur and the other will fail with -EEXIST. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Separate out trace events from global variablesSteven Rostedt2013-03-151-243/+533
| | | | | | | | | | | | | | | | The trace events for ftrace are all defined via global variables. The arrays of events and event systems are linked to a global list. This prevents multiple users of the event system (what to enable and what not to). By adding descriptors to represent the event/file relation, as well as to which trace_array descriptor they are associated with, allows for more than one set of events to be defined. Once the trace events files have a link between the trace event and the trace_array they are associated with, we can create multiple trace_arrays that can record separate events in separate buffers. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Remove the extra 4 bytes of padding in eventsSteven Rostedt2013-01-211-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Due to a userspace issue with PowerTop v2beta, which hardcoded the offset of event fields that it was using, it broke when we removed the Big Kernel Lock counter from the event header. (commit e6e1e2593 "tracing: Remove lock_depth from event entry") Because this broke userspace, it was determined that we must keep those 4 bytes around. (commit a3a4a5acd "Regression: partial revert "tracing: Remove lock_depth from event entry"") This unfortunately wastes space in the ring buffer. 4 bytes per event, where a lot of events are just 24 bytes. That's 16% of the buffer wasted. A million events will add 4 megs of white space into the buffer. It was later noticed that PowerTop v2beta could not work on systems where the kernel was 64 bit but the userspace was 32 bits. The reason was because the offsets are different between the two and the hard coded offset of one would not work with the other. With PowerTop v2 final, it implemented the same interface that both perf and trace-cmd use. That is, it reads the format file of the event to find the offsets of the fields it needs. This fixes the problem with running powertop on a 32 bit userspace running on a 64 bit kernel. It also no longer requires the 4 byte padding. As PowerTop v2 has been out for a while, and is included in all major distributions, it is time that we can safely remove the 4 bytes of padding. Users of PowerTop v2beta should upgrade to PowerTop v2 final. Cc: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Use irq_work for wake ups and remove *_nowake_*() functionsSteven Rostedt2012-11-021-1/+1
| | | | | | | | | | | | | | | | | | Have the ring buffer commit function use the irq_work infrastructure to wake up any waiters waiting on the ring buffer for new data. The irq_work was created for such a purpose, where doing the actual wake up at the time of adding data is too dangerous, as an event or function trace may be in the midst of the work queue locks and cause deadlocks. The irq_work will either delay the action to the next timer interrupt, or trigger an IPI to itself forcing an interrupt to do the work (in a safe location). With irq_work, all ring buffer commits can safely do wakeups, removing the need for the ring buffer commit "nowake" variants, which were used by events and function tracing. All commits can now safely use the normal commit, and the "nowake" variants can be removed. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Separate open function from set_event and available_eventsSteven Rostedt2012-11-021-19/+27
| | | | | | | | | | | | | | The open function used by available_events is the same as set_event even though it uses different seq functions. This causes a side effect of writing into available_events clearing all events, even though available_events is suppose to be read only. There's no reason to keep a single function for just the open and have both use different functions for everything else. It is a little confusing and causes strange behavior. Just have each have their own function. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* tracing: Enable comm recording if trace_printk() is usedSteven Rostedt2012-10-311-0/+3
| | | | | | | | | | | | | | | | | | | | | | If comm recording is not enabled when trace_printk() is used then you just get this type of output: [ adding trace_printk("hello! %d", irq); in do_IRQ ] <...>-2843 [001] d.h. 80.812300: do_IRQ: hello! 14 <...>-2734 [002] d.h2 80.824664: do_IRQ: hello! 14 <...>-2713 [003] d.h. 80.829971: do_IRQ: hello! 14 <...>-2814 [000] d.h. 80.833026: do_IRQ: hello! 14 By enabling the comm recorder when trace_printk is enabled: hackbench-6715 [001] d.h. 193.233776: do_IRQ: hello! 21 sshd-2659 [001] d.h. 193.665862: do_IRQ: hello! 21 <idle>-0 [001] d.h1 193.665996: do_IRQ: hello! 21 Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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