summaryrefslogtreecommitdiffstats
path: root/kernel/futex.c
Commit message (Collapse)AuthorAgeFilesLines
* futex: Fix handling of bad requeue syscall pairingDarren Hart2009-08-101-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | If futex_requeue(requeue_pi=1) finds a futex_q that was created by a call other the futex_wait_requeue_pi(), the q.rt_waiter may be null. If so, this will result in an oops from the following call graph: futex_requeue() rt_mutex_start_proxy_lock() task_blocks_on_rt_mutex() waiter->task dereference OOPS We currently WARN_ON() if this is detected, clearly this is inadequate. If we detect a mispairing in futex_requeue(), bail out, seding -EINVAL to user-space. V2: Fix parenthesis warnings. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: John Kacur <jkacur@redhat.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> Cc: John Stultz <johnstul@linux.vnet.ibm.com> LKML-Reference: <4A7CA8C0.7010809@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: Update futex_q lock_ptr on requeue proxy lockDarren Hart2009-08-101-4/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | futex_requeue() can acquire the lock on behalf of a waiter early on or during the requeue loop if it is uncontended or in the event of a lock steal or owner died. On wakeup, the waiter (in futex_wait_requeue_pi()) cleans up the pi_state owner using the lock_ptr to protect against concurrent access to the pi_state. The pi_state is hung off futex_q's on the requeue target futex hash bucket so the lock_ptr needs to be updated accordingly. The problem manifested by triggering the WARN_ON in lookup_pi_state() about the pid != pi_state->owner->pid. With this patch, the pi_state is properly guarded against concurrent access via the requeue target hb lock. The astute reviewer may notice that there is a window of time between when futex_requeue() unlocks the hb locks and when futex_wait_requeue_pi() will acquire hb2->lock. During this time the pi_state and uval are not in sync with the underlying rtmutex owner (but the uval does indicate there are waiters, so no atomic changes will occur in userspace). However, this is not a problem. Should a contending thread enter lookup_pi_state() and acquire hb2->lock before the ownership is fixed up, it will find the pi_state hung off a waiter's (possibly the pending owner's) futex_q and block on the rtmutex. Once futex_wait_requeue_pi() fixes up the owner, it will also move the pi_state from the old owner's task->pi_state_list to its own. v3: Fix plist lock name for application to mainline (rather than -rt) Compile tested against tip/v2.6.31-rc5. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> Cc: John Stultz <johnstul@linux.vnet.ibm.com> LKML-Reference: <4A7F4EFF.6090903@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futexes: Fix infinite loop in get_futex_key() on huge pageSonny Rao2009-07-111-0/+1
| | | | | | | | | | | | | | | | | | | | | | | get_futex_key() can infinitely loop if it is called on a virtual address that is within a huge page but not aligned to the beginning of that page. The call to get_user_pages_fast will return the struct page for a sub-page within the huge page and the check for page->mapping will always fail. The fix is to call compound_head on the page before checking that it's mapped. Signed-off-by: Sonny Rao <sonnyrao@us.ibm.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org Cc: anton@samba.org Cc: rajamony@us.ibm.com Cc: speight@us.ibm.com Cc: mstephen@us.ibm.com Cc: grimm@us.ibm.com Cc: mikey@ozlabs.au.ibm.com LKML-Reference: <20090710231313.GA23572@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: request only one page from get_user_pages()Thomas Gleixner2009-06-251-1/+1
| | | | | | | | | | | | | Yanmin noticed that fault_in_user_writeable() requests 4 pages instead of one. That's the result of blindly trusting Linus' proposal :) I even looked up the prototype to verify the correctness: the argument in question is confusingly enough named "len" while in reality it means number of pages. Pointed-out-by: Yanmin Zhang <yanmin_zhang@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* futex: Fix the write access fault problem for realThomas Gleixner2009-06-241-21/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 64d1304a64 (futex: setup writeable mapping for futex ops which modify user space data) did address only half of the problem of write access faults. The patch was made on two wrong assumptions: 1) access_ok(VERIFY_WRITE,...) would actually check write access. On x86 it does _NOT_. It's a pure address range check. 2) a RW mapped region can not go away under us. That's wrong as well. Nobody can prevent another thread to call mprotect(PROT_READ) on that region where the futex resides. If that call hits between the get_user_pages_fast() verification and the actual write access in the atomic region we are toast again. The solution is to not rely on access_ok and get_user() for any write access related fault on private and shared futexes. Instead we need to fault it in with verification of write access. There is no generic non destructive write mechanism which would fault the user page in trough a #PF, but as we already know that we will fault we can as well call get_user_pages() directly and avoid the #PF overhead. If get_user_pages() returns -EFAULT we know that we can not fix it anymore and need to bail out to user space. Remove a bunch of confusing comments on this issue as well. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org
* futex: fix restart in wait_requeue_piThomas Gleixner2009-05-201-40/+9
| | | | | | | | | | | | | | | | | | | | | If the waiter has been requeued to the outer PI futex and is interrupted by a signal and the thread handles the signal then ERESTART_RESTARTBLOCK is changed to EINTR and the restart block is discarded. That way we return an unexcpected EINTR to user space instead of ending up in futex_lock_pi_restart. But we do not need to restart the syscall because we know that the condition has changed since we have been requeued. If we would simply restart the syscall then we would drop out via the comparison of the user space value with EWOULDBLOCK. The user space side needs to handle EWOULDBLOCK anyway as the enqueueing on the inner futex can race with a requeue/wake. So we can simply return EWOULDBLOCK to user space which also signals that we did not take the outer futex and let user space handle it in the same way it has to handle the requeue/wake race. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* futex: fix restart for early wakeup in futex_wait_requeue_pi()Thomas Gleixner2009-05-201-10/+3
| | | | | | | | | The futex_wait_requeue_pi op should restart unconditionally like futex_lock_pi. The user of that function e.g. pthread_cond_wait can not be interrupted so we do not care about the SA_RESTART flag of the signal. Clean up the FIXMEs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* futex: cleanup error exitThomas Gleixner2009-05-201-4/+3
| | | | | | Reuse the put_key_ref(key2) call in the exit path. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Merge branch 'core/urgent' into core/futexesThomas Gleixner2009-05-201-13/+21
|\ | | | | | | | | | | | | | | | | | | Merge reason: this branch was on an pre -rc1 base, merge it up to -rc6+ to get the latest upstream fixes. Conflicts: kernel/futex.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * futex: setup writeable mapping for futex ops which modify user space dataThomas Gleixner2009-05-191-11/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The futex code installs a read only mapping via get_user_pages_fast() even if the futex op function has to modify user space data. The eventual fault was fixed up by futex_handle_fault() which walked the VMA with mmap_sem held. After the cleanup patches which removed the mmap_sem dependency of the futex code commit 4dc5b7a36a49eff97050894cf1b3a9a02523717 (futex: clean up fault logic) removed the private VMA walk logic from the futex code. This change results in a stale RO mapping which is not fixed up. Instead of reintroducing the previous fault logic we set up the mapping in get_user_pages_fast() read/write for all operations which modify user space data. Also handle private futexes in the same way and make the current unconditional access_ok(VERIFY_WRITE) depend on the futex op. Reported-by: Andreas Schwab <schwab@linux-m68k.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> CC: stable@kernel.org
| * futex: comment requeue key reference semanticsDarren Hart2009-04-021-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | We've tripped over the futex_requeue drop_count refering to key2 instead of key1. The code is actually correct, but is non-intuitive. This patch adds an explicit comment explaining the requeue. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | futex: remove the wait queueThomas Gleixner2009-05-151-33/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The waitqueue which is used in struct futex_q is a leftover from the futexfd implementation. There is no need to use a waitqueue at all, as the waiting task is the only user of it. The waitqueue just adds additional locking and a loop in the wake up path which both can be avoided. We have already a task reference in struct futex_q which is used for PI futexes. Use it for normal futexes as well and just wake up the task directly. The logic of signalling the futex wakeup via setting q->lock_ptr to NULL is kept with the difference that we set it NULL before doing the wakeup. This opens an exit race window vs. a non futex wake up of the to be woken up task, which we prevent with get_task_struct / put_task_struct on the waiter. [ Impact: simplification ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: remove FUTEX_REQUEUE_PI (non CMP)Darren Hart2009-04-301-5/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The new requeue PI futex op codes were modeled after the existing FUTEX_REQUEUE and FUTEX_CMP_REQUEUE calls. I was unaware at the time that FUTEX_REQUEUE was only around for compatibility reasons and shouldn't be used in new code. Ulrich Drepper elaborates on this in his Futexes are Tricky paper: http://people.redhat.com/drepper/futex.pdf. The deprecated call doesn't catch changes to the futex corresponding to the destination futex which can lead to deadlock. Therefor, I feel it best to remove FUTEX_REQUEUE_PI and leave only FUTEX_CMP_REQUEUE_PI as there are not yet any existing users of the API. This patch does change the OP code value of FUTEX_CMP_REQUEUE_PI to 12 from 13. Since my test case is the only known user of this API, I felt this was the right thing to do, rather than leave a hole in the enumeration. I chose to continue using the _CMP_ modifier in the OP code to make it explicit to the user that the test is being done. Builds, boots, and ran several hundred iterations requeue_pi.c. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> LKML-Reference: <49ED580E.1050502@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: fix futex_wait_setup key handlingDarren Hart2009-04-101-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | If the get_futex_key() call were to fail, the existing code would try and put_futex_key() prior to returning. This patch makes sure we only put_futex_key() if get_futex_key() succeeded. Reported-by: Clark Williams <williams@redhat.com> Signed-off-by: Darren Hart <dvhltc@us.ibm.com> LKML-Reference: <20090410165005.14342.16973.stgit@Aeon> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: fixup unlocked requeue pi caseDarren Hart2009-04-081-21/+44
| | | | | | | | | | | | | | | | | | | | Thomas's testing caught a problem when the requeue target futex is unowned and multiple tasks are requeued to it. This patch ensures the FUTEX_WAITERS bit gets set if futex_requeue() will requeue one or more tasks in addition to the one acquiring the lock. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: add requeue_pi functionalityDarren Hart2009-04-061-19/+500
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | PI Futexes and their underlying rt_mutex cannot be left ownerless if there are pending waiters as this will break the PI boosting logic, so the standard requeue commands aren't sufficient. The new commands properly manage pi futex ownership by ensuring a futex with waiters has an owner at all times. This will allow glibc to properly handle pi mutexes with pthread_condvars. The approach taken here is to create two new futex op codes: FUTEX_WAIT_REQUEUE_PI: Tasks will use this op code to wait on a futex (such as a non-pi waitqueue) and wake after they have been requeued to a pi futex. Prior to returning to userspace, they will acquire this pi futex (and the underlying rt_mutex). futex_wait_requeue_pi() is the result of a high speed collision between futex_wait() and futex_lock_pi() (with the first part of futex_lock_pi() being done by futex_proxy_trylock_atomic() on behalf of the top_waiter). FUTEX_REQUEUE_PI (and FUTEX_CMP_REQUEUE_PI): This call must be used to wake tasks waiting with FUTEX_WAIT_REQUEUE_PI, regardless of how many tasks the caller intends to wake or requeue. pthread_cond_broadcast() should call this with nr_wake=1 and nr_requeue=INT_MAX. pthread_cond_signal() should call this with nr_wake=1 and nr_requeue=0. The reason being we need both callers to get the benefit of the futex_proxy_trylock_atomic() routine. futex_requeue() also enqueues the top_waiter on the rt_mutex via rt_mutex_start_proxy_lock(). Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: split out futex value validation codeDarren Hart2009-04-061-44/+72
| | | | | | | | | | | | | | | | | | Refactor the code to validate the expected futex value in order to reuse it with the requeue_pi code. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: distangle futex_requeue()Darren Hart2009-04-061-14/+29
| | | | | | | | | | | | | | | | | | | | | | futex_requeue() is getting a bit long-winded, and will be getting more so after the requeue_pi patch. Factor out the actual requeueing into a nicely contained inline function to reduce function length and improve legibility. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: add FUTEX_HAS_TIMEOUT flag to restart.futex.flagsDarren Hart2009-04-061-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently restart is only used if there is a timeout. The requeue_pi functionality requires restarting to futex_lock_pi() on signal after wakeup in futex_wait_requeue_pi() regardless of if there was a timeout or not. Using 0 for the timeout value is confusing as that could indicate an expired timer. The flag makes this explicit. While the check is not technically needed in futex_wait_restart(), doing so makes the code consistent with and will avoid confusion should the need arise to restart wait without a timeout. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: split out fixup owner logic from futex_lock_pi()Darren Hart2009-04-061-69/+89
| | | | | | | | | | | | | | | | | | Refactor the post lock acquisition logic from futex_lock_pi(). This code will be reused in futex_wait_requeue_pi(). Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: split out atomic logic from futex_lock_pi()Darren Hart2009-04-061-94/+130
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Refactor the atomic portion of futex_lock_pi() into futex_lock_pi_atomic(). This logic will be needed by requeue_pi, so modularize it to reduce code duplication. The only significant change is passing of the task to try and take the lock for. This simplifies the -EDEADLK test as if the lock is owned by task t, it's a deadlock, regardless of if we are doing requeue pi or not. This patch updates the corresponding comment accordingly. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: add helper to find the top prio waiter of a futexDarren Hart2009-04-061-0/+19
| | | | | | | | | | | | | | | | | | Improve legibility by wrapping finding the top waiter in a function. This will be used by the follow-on patches for enabling requeue pi. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | futex: separate futex_wait_queue_me() logic from futex_wait()Darren Hart2009-04-061-62/+76
|/ | | | | | | | | | | Refactor futex_wait() in preparation for futex_wait_requeue_pi(). In order to reuse a good chunk of the futex_wait() code for the upcoming futex_wait_requeue_pi() function, this patch breaks out the queue-to-wakeup section of futex_wait() into futex_wait_queue_me(). Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* futex: remove the pointer math from double_unlock_hb, fixIngo Molnar2009-03-131-1/+2
| | | | | | | | | | | | | Impact: fix double unlock crash Thomas Gleixner noticed that the simplified double_unlock_hb() became ... too unsophisticated: in the hb1 == hb2 case it will do a double unlock. Reported-by: Thomas Gleixner <tglx@linutronix.de> Cc: Darren Hart <dvhltc@us.ibm.com> LKML-Reference: <20090312221118.11146.68610.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: remove the pointer math from double_unlock_hbDarren Hart2009-03-131-8/+2
| | | | | | | | | | | | | | Impact: simplify code I mistakenly included the pointer value ordering in the double_unlock_hb() in my previous patch. It's only necessary in the double_lock_hb() function. This patch removes it. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <20090312221118.11146.68610.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: clean up fault logicDarren Hart2009-03-121-90/+36
| | | | | | | | | | | | | | | | | | | | | Impact: cleanup Older versions of the futex code held the mmap_sem which had to be dropped in order to call get_user(), so a two-pronged fault handling mechanism was employed to handle faults of the atomic operations. The mmap_sem is no longer held, so get_user() should be adequate. This patch greatly simplifies the logic and improves legibility. Build and boot tested on a 4 way Intel x86_64 workstation. Passes basic pthread_mutex and PI tests out of ltp/testcases/realtime. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <20090312075612.9856.48612.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: unlock before returning -EFAULTDarren Hart2009-03-121-0/+7
| | | | | | | | | | | | | | | | | | | | | Impact: rt-mutex failure case fix futex_lock_pi can potentially return -EFAULT with the rt_mutex held. This seems like the wrong thing to do as userspace should assume -EFAULT means the lock was not taken. Even if it could figure this out, we'd be leaving the pi_state->owner in an inconsistent state. This patch unlocks the rt_mutex prior to returning -EFAULT to userspace. Build and boot tested on a 4 way Intel x86_64 workstation. Passes basic pthread_mutex and PI tests out of ltp/testcases/realtime. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <20090312075606.9856.88729.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: use current->time_slack_ns for rt tasks tooDarren Hart2009-03-121-5/+2
| | | | | | | | | | | | | | | | | RT tasks should set their timer slack to 0 on their own. This patch removes the 'if (rt_task()) slack = 0;' block in futex_wait. Build and boot tested on a 4 way Intel x86_64 workstation. Passes basic pthread_mutex and PI tests out of ltp/testcases/realtime. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Arjan van de Ven <arjan@linux.intel.com> LKML-Reference: <20090312075559.9856.28822.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: add double_unlock_hb()Darren Hart2009-03-121-12/+17
| | | | | | | | | | | | | | | | | | | | | Impact: cleanup The futex code uses double_lock_hb() which locks the hb->lock's in pointer value order. There is no parallel unlock routine, and the code unlocks them in name order, ignoring pointer value. This patch adds double_unlock_hb() to refactor the duplicated code segments. Build and boot tested on a 4 way Intel x86_64 workstation. Passes basic pthread_mutex and PI tests out of ltp/testcases/realtime. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <20090312075552.9856.48021.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: additional (get|put)_futex_key() fixesDarren Hart2009-03-121-5/+11
| | | | | | | | | | | | | | | | | | | Impact: fix races futex_requeue and futex_lock_pi still had some bad (get|put)_futex_key() usage. This patch adds the missing put_futex_keys() and corrects a goto in futex_lock_pi() to avoid a double get. Build and boot tested on a 4 way Intel x86_64 workstation. Passes basic pthread_mutex and PI tests out of ltp/testcases/realtime. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <20090312075545.9856.75152.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: update futex commentaryDarren Hart2009-03-121-19/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: cleanup The futex_hash_bucket can be a bit confusing when first looking at the code as it is a shared queue (and futex_q isn't a queue at all, but rather an element on the queue). The mmap_sem is no longer held outside of the futex_handle_fault() routine, yet numerous comments refer to it. The fshared argument is no an integer. I left some of these comments along as they are simply removed in future patches. Some of the commentary refering to futexes by virtual page mappings was not very clear, and completely accurate (as for shared futexes both the page and the offset are used to determine the key). For the purposes of the function description, just referring to "the futex" seems sufficient. With hashed futexes we now access the page after the hash-bucket is locked, and not only after it is enqueued. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <20090312075537.9856.29954.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* futex: fix reference leakPeter Zijlstra2009-02-111-25/+28
| | | | | | | | | | | | | | | | Catalin noticed that (38d47c1b7075: futex: rely on get_user_pages() for shared futexes) caused an mm_struct leak. Some tracing with the function graph tracer quickly pointed out that futex_wait() has exit paths with unbalanced reference counts. This regression was discovered by kmemleak. Reported-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com> Tested-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* [CVE-2009-0029] System call wrappers part 31Heiko Carstens2009-01-141-6/+5
| | | | Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
* [CVE-2009-0029] System call wrappers part 08Heiko Carstens2009-01-141-3/+3
| | | | Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
*-. Merge branches 'core/futexes', 'core/locking', 'core/rcu' and 'linus' into ↵Ingo Molnar2009-01-061-32/+40
|\ \ | | | | | | | | | core/urgent
| * | futex: catch certain assymetric (get|put)_futex_key callsDarren Hart2009-01-021-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: add debug check Following up on my previous key reference accounting patches, this patch will catch puts on keys that haven't been "got". This won't catch nested get/put mismatches though. Build and boot tested, with minimal desktop activity and a run of the open_posix_testsuite in LTP for testing. No warnings logged. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | futex: make futex_(get|put)_key() calls symmetricDarren Hart2008-12-301-31/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: cleanup This patch makes the calls to futex_get_key_refs() and futex_drop_key_refs() explicitly symmetric by only "putting" keys we successfully "got". Also cleanup a couple return points that didn't "put" after a successful "get". Build and boot tested on an x86_64 system. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | Merge branch 'core-for-linus' of ↵Linus Torvalds2008-12-301-215/+136
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (63 commits) stacktrace: provide save_stack_trace_tsk() weak alias rcu: provide RCU options on non-preempt architectures too printk: fix discarding message when recursion_bug futex: clean up futex_(un)lock_pi fault handling "Tree RCU": scalable classic RCU implementation futex: rename field in futex_q to clarify single waiter semantics x86/swiotlb: add default swiotlb_arch_range_needs_mapping x86/swiotlb: add default phys<->bus conversion x86: unify pci iommu setup and allow swiotlb to compile for 32 bit x86: add swiotlb allocation functions swiotlb: consolidate swiotlb info message printing swiotlb: support bouncing of HighMem pages swiotlb: factor out copy to/from device swiotlb: add arch hook to force mapping swiotlb: allow architectures to override phys<->bus<->phys conversions swiotlb: add comment where we handle the overflow of a dma mask on 32 bit rcu: fix rcutorture behavior during reboot resources: skip sanity check of busy resources swiotlb: move some definitions to header swiotlb: allow architectures to override swiotlb pool allocation ... Fix up trivial conflicts in arch/x86/kernel/Makefile arch/x86/mm/init_32.c include/linux/hardirq.h as per Ingo's suggestions.
| * | futex: clean up futex_(un)lock_pi fault handlingDarren Hart2008-12-191-14/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: cleanup Some apparently left over cruft code was complicating the fault logic: Testing if uval != -EFAULT doesn't have any meaning, get_user() sets ret to either 0 or -EFAULT, there's no need to compare uval, especially not against EFAULT which it will never be. This patch removes the superfluous test and clarifies the comment blocks. Build and boot tested on an 8way x86_64 system. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | futex: rename field in futex_q to clarify single waiter semanticsDarren Hart2008-12-181-5/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: simplify code I've tripped over the naming of this field a couple times. The futex_q uses a "waiters" list to represent a single blocked task and then calles wake_up_all(). This can lead to confusion in trying to understand the intent of the code, which is to have a single futex_q for every task waiting on a futex. This patch corrects the problem, using a single pointer to the waiting task, and an appropriate call to wake_up, rather than wake_up_all. Compile and boot tested on an 8way x86_64 machine. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | futex: make clock selectable for FUTEX_WAIT_BITSETThomas Gleixner2008-11-241-7/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | FUTEX_WAIT_BITSET could be used instead of FUTEX_WAIT by setting the bit set to FUTEX_BITSET_MATCH_ANY, but FUTEX_WAIT uses CLOCK_REALTIME while FUTEX_WAIT_BITSET uses CLOCK_MONOTONIC. Add a flag to select CLOCK_REALTIME for FUTEX_WAIT_BITSET so glibc can replace the FUTEX_WAIT logic which needs to do gettimeofday() calls before and after the syscall to convert the absolute timeout to a relative timeout for FUTEX_WAIT. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Ulrich Drepper <drepper@redhat.com>
| * | Merge branch 'linus' into core/futexesThomas Gleixner2008-11-241-4/+7
| |\|
| * | futex: fixup get_futex_key() for private futexesPeter Zijlstra2008-09-301-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | With the get_user_pages_fast() patches we made get_futex_key() obtain a reference on the returned key, but failed to do so for private futexes. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | futex: cleanup fsharedPeter Zijlstra2008-09-301-29/+19
| | | | | | | | | | | | | | | | | | | | | | | | fshared doesn't need to be a rw_sem pointer anymore, so clean that up. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | futex: use fast_gup()Peter Zijlstra2008-09-301-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | Change the get_user_pages() call with fast_gup() which doesn't require holding the mmap_sem thereby removing the mmap_sem from all fast paths. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | futex: reduce mmap_sem usagePeter Zijlstra2008-09-301-79/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | now that we rely on get_user_pages() for the shared key handling move all the mmap_sem stuff closely around the slow paths. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | futex: rely on get_user_pages() for shared futexesPeter Zijlstra2008-09-301-82/+80
| | | | | | | | | | | | | | | | | | | | | | | | | | | On the way of getting rid of the mmap_sem requirement for shared futexes, start by relying on get_user_pages(). Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | CRED: Use RCU to access another task's creds and to release a task's own credsDavid Howells2008-11-141-8/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use RCU to access another task's creds and to release a task's own creds. This means that it will be possible for the credentials of a task to be replaced without another task (a) requiring a full lock to read them, and (b) seeing deallocated memory. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* | | CRED: Separate task security context from task_structDavid Howells2008-11-141-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Separate the task security context from task_struct. At this point, the security data is temporarily embedded in the task_struct with two pointers pointing to it. Note that the Alpha arch is altered as it refers to (E)UID and (E)GID in entry.S via asm-offsets. With comment fixes Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* | | CRED: Wrap task credential accesses in the core kernelDavid Howells2008-11-141-3/+5
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Wrap access to task credentials so that they can be separated more easily from the task_struct during the introduction of COW creds. Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id(). Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more sense to use RCU directly rather than a convenient wrapper; these will be addressed by later patches. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-audit@redhat.com Cc: containers@lists.linux-foundation.org Cc: linux-mm@kvack.org Signed-off-by: James Morris <jmorris@namei.org>
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-15 20:31:57 +0000