kernel/linux.git/include/linux/ww_mutex.h, branch v6.19.11

locking/ww_mutex: Fix ww_mutex dummy lockdep map selftest warnings

2024-12-02T11:16:57+00:00

The below commit introduces a dummy lockdep map, but didn't get the initialization quite right (it should mimic the initialization of the real ww_mutex lockdep maps). It also introduced a separate locking api selftest failure. Fix these. Closes: https://lore.kernel.org/lkml/Zw19sMtnKdyOVQoh@boqun-archlinux/ Fixes: 823a566221a5 ("locking/ww_mutex: Adjust to lockdep nest_lock requirements") Reported-by: Boqun Feng Suggested-by: Boqun Feng Signed-off-by: Thomas Hellström Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20241127085430.3045-1-thomas.hellstrom@linux.intel.com

locking/ww_mutex: Adjust to lockdep nest_lock requirements

2024-10-09T13:08:25+00:00

When using mutex_acquire_nest() with a nest_lock, lockdep refcounts the number of acquired lockdep_maps of mutexes of the same class, and also keeps a pointer to the first acquired lockdep_map of a class. That pointer is then used for various comparison-, printing- and checking purposes, but there is no mechanism to actively ensure that lockdep_map stays in memory. Instead, a warning is printed if the lockdep_map is freed and there are still held locks of the same lock class, even if the lockdep_map itself has been released. In the context of WW/WD transactions that means that if a user unlocks and frees a ww_mutex from within an ongoing ww transaction, and that mutex happens to be the first ww_mutex grabbed in the transaction, such a warning is printed and there might be a risk of a UAF. Note that this is only problem when lockdep is enabled and affects only dereferences of struct lockdep_map. Adjust to this by adding a fake lockdep_map to the acquired context and make sure it is the first acquired lockdep map of the associated ww_mutex class. Then hold it for the duration of the WW/WD transaction. This has the side effect that trying to lock a ww mutex *without* a ww_acquire_context but where a such context has been acquire, we'd see a lockdep splat. The test-ww_mutex.c selftest attempts to do that, so modify that particular test to not acquire a ww_acquire_context if it is not going to be used. Signed-off-by: Thomas Hellström Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20241009092031.6356-1-thomas.hellstrom@linux.intel.com

kernel/locking: Add context to ww_mutex_trylock()

2021-09-17T13:08:41+00:00

i915 will soon gain an eviction path that trylock a whole lot of locks for eviction, getting dmesg failures like below: BUG: MAX_LOCK_DEPTH too low! turning off the locking correctness validator. depth: 48 max: 48! 48 locks held by i915_selftest/5776: #0: ffff888101a79240 (&dev->mutex){....}-{3:3}, at: __driver_attach+0x88/0x160 #1: ffffc900009778c0 (reservation_ww_class_acquire){+.+.}-{0:0}, at: i915_vma_pin.constprop.63+0x39/0x1b0 [i915] #2: ffff88800cf74de8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_vma_pin.constprop.63+0x5f/0x1b0 [i915] #3: ffff88810c7f9e38 (&vm->mutex/1){+.+.}-{3:3}, at: i915_vma_pin_ww+0x1c4/0x9d0 [i915] #4: ffff88810bad5768 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915] #5: ffff88810bad60e8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915] ... #46: ffff88811964d768 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915] #47: ffff88811964e0e8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915] INFO: lockdep is turned off. Fixing eviction to nest into ww_class_acquire is a high priority, but it requires a rework of the entire driver, which can only be done one step at a time. As an intermediate solution, add an acquire context to ww_mutex_trylock, which allows us to do proper nesting annotations on the trylocks, making the above lockdep splat disappear. This is also useful in regulator_lock_nested, which may avoid dropping regulator_nesting_mutex in the uncontended path, so use it there. TTM may be another user for this, where we could lock a buffer in a fastpath with list locks held, without dropping all locks we hold. [peterz: rework actual ww_mutex_trylock() implementations] Signed-off-by: Maarten Lankhorst Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/YUBGPdDDjKlxAuXJ@hirez.programming.kicks-ass.net

locking/ww_mutex: Add rt_mutex based lock type and accessors

2021-08-17T17:05:11+00:00

Provide the defines for RT mutex based ww_mutexes and fix up the debug logic so it's either enabled by DEBUG_MUTEXES or DEBUG_RT_MUTEXES on RT kernels. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210815211304.908012566@linutronix.de

locking/ww_mutex: Abstract out internal lock accesses

2021-08-17T17:05:03+00:00

Accessing the internal wait_lock of mutex and rtmutex is slightly different. Provide helper functions for that. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210815211304.734635961@linutronix.de

locking/ww_mutex: Move the ww_mutex definitions from into

2021-08-17T16:24:31+00:00

Move the ww_mutex definitions into the ww_mutex specific header where they belong. Preparatory change to allow compiling ww_mutexes standalone. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210815211304.110216293@linutronix.de

locking/ww_mutex: Remove DEFINE_WW_MUTEX() macro

2021-03-19T11:13:10+00:00

The current DEFINE_WW_MUTEX() macro fails to properly set up the lockdep key of the ww_mutexes causing potential circular locking dependency splat. Though it is possible to add more macro magic to make it work, but the result is rather ugly. Since locktorture was the only user of DEFINE_WW_MUTEX() and the previous commit has just removed its use. It is easier to just remove the macro to force future users of ww_mutexes to use ww_mutex_init() for initialization. Suggested-by: Peter Zijlstra Signed-off-by: Waiman Long Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210318172814.4400-4-longman@redhat.com

locking/ww_mutex: Fix acquire/release imbalance in ww_acquire_init()/ww_acquire_fini()

2021-03-17T08:56:45+00:00

In ww_acquire_init(), mutex_acquire() is gated by CONFIG_DEBUG_LOCK_ALLOC. The dep_map in the ww_acquire_ctx structure is also gated by the same config. However mutex_release() in ww_acquire_fini() is gated by CONFIG_DEBUG_MUTEXES. It is possible to set CONFIG_DEBUG_MUTEXES without setting CONFIG_DEBUG_LOCK_ALLOC though it is an unlikely configuration. That may cause a compilation error as dep_map isn't defined in this case. Fix this potential problem by enclosing mutex_release() inside CONFIG_DEBUG_LOCK_ALLOC. Signed-off-by: Waiman Long Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210316153119.13802-3-longman@redhat.com

locking/seqlock, headers: Untangle the spaghetti monster

2020-08-06T14:13:13+00:00

By using lockdep_assert_*() from seqlock.h, the spaghetti monster attacked. Attack back by reducing seqlock.h dependencies from two key high level headers: - : -Remove - : -Remove - : +Add The price was to add it to sched.h ... Core header fallout, we add direct header dependencies instead of gaining them parasitically from higher level headers: - : +Add - : +Add - : +Add - : +Add - : +Add - : +Add Arch headers fallout: - PARISC: : +Add - SH: : +Add - SPARC: : +Add - SPARC: : +Add , -Remove - X86: : +Add -Remove There's also a bunch of parasitic header dependency fallout in .c files, not listed separately. [ mingo: Extended the changelog, split up & fixed the original patch. ] Co-developed-by: Ingo Molnar Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200804133438.GK2674@hirez.programming.kicks-ass.net

locking/lockdep: Remove unused @nested argument from lock_release()

2019-10-09T10:46:10+00:00

Since the following commit: b4adfe8e05f1 ("locking/lockdep: Remove unused argument in __lock_release") @nested is no longer used in lock_release(), so remove it from all lock_release() calls and friends. Signed-off-by: Qian Cai Signed-off-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Acked-by: Daniel Vetter Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: alexander.levin@microsoft.com Cc: daniel@iogearbox.net Cc: davem@davemloft.net Cc: dri-devel@lists.freedesktop.org Cc: duyuyang@gmail.com Cc: gregkh@linuxfoundation.org Cc: hannes@cmpxchg.org Cc: intel-gfx@lists.freedesktop.org Cc: jack@suse.com Cc: jlbec@evilplan.or Cc: joonas.lahtinen@linux.intel.com Cc: joseph.qi@linux.alibaba.com Cc: jslaby@suse.com Cc: juri.lelli@redhat.com Cc: maarten.lankhorst@linux.intel.com Cc: mark@fasheh.com Cc: mhocko@kernel.org Cc: mripard@kernel.org Cc: ocfs2-devel@oss.oracle.com Cc: rodrigo.vivi@intel.com Cc: sean@poorly.run Cc: st@kernel.org Cc: tj@kernel.org Cc: tytso@mit.edu Cc: vdavydov.dev@gmail.com Cc: vincent.guittot@linaro.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw Signed-off-by: Ingo Molnar