History log of /linux-6.15/kernel/locking/ww_rt_mutex.c (Results 1 – 4 of 4)
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# af9f0063 08-Sep-2023 Sebastian Andrzej Siewior <[email protected]>

locking/rtmutex: Avoid unconditional slowpath for DEBUG_RT_MUTEXES

With DEBUG_RT_MUTEXES enabled the fast-path rt_mutex_cmpxchg_acquire()
always fails and all lock operations take the slow path.

Pr

locking/rtmutex: Avoid unconditional slowpath for DEBUG_RT_MUTEXES

With DEBUG_RT_MUTEXES enabled the fast-path rt_mutex_cmpxchg_acquire()
always fails and all lock operations take the slow path.

Provide a new helper inline rt_mutex_try_acquire() which maps to
rt_mutex_cmpxchg_acquire() in the non-debug case. For the debug case
it invokes rt_mutex_slowtrylock() which can acquire a non-contended
rtmutex under full debug coverage.

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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Revision tags: v6.5, v6.5-rc7, v6.5-rc6, v6.5-rc5, v6.5-rc4, v6.5-rc3, v6.5-rc2, v6.5-rc1, v6.4, v6.4-rc7, v6.4-rc6, v6.4-rc5, v6.4-rc4, v6.4-rc3, v6.4-rc2, v6.4-rc1, v6.3, v6.3-rc7, v6.3-rc6, v6.3-rc5, v6.3-rc4, v6.3-rc3, v6.3-rc2, v6.3-rc1, v6.2, v6.2-rc8, v6.2-rc7, v6.2-rc6, v6.2-rc5, v6.2-rc4, v6.2-rc3, v6.2-rc2, v6.2-rc1, v6.1, v6.1-rc8, v6.1-rc7, v6.1-rc6, v6.1-rc5, v6.1-rc4, v6.1-rc3, v6.1-rc2, v6.1-rc1, v6.0, v6.0-rc7, v6.0-rc6, v6.0-rc5, v6.0-rc4, v6.0-rc3, v6.0-rc2, v6.0-rc1, v5.19, v5.19-rc8, v5.19-rc7, v5.19-rc6, v5.19-rc5, v5.19-rc4, v5.19-rc3, v5.19-rc2, v5.19-rc1, v5.18, v5.18-rc7, v5.18-rc6, v5.18-rc5, v5.18-rc4, v5.18-rc3, v5.18-rc2, v5.18-rc1, v5.17, v5.17-rc8, v5.17-rc7, v5.17-rc6, v5.17-rc5, v5.17-rc4, v5.17-rc3, v5.17-rc2, v5.17-rc1, v5.16, v5.16-rc8, v5.16-rc7, v5.16-rc6, v5.16-rc5, v5.16-rc4, v5.16-rc3, v5.16-rc2, v5.16-rc1
# 2202e15b 04-Nov-2021 Sebastian Andrzej Siewior <[email protected]>

kernel/locking: Use a pointer in ww_mutex_trylock().

mutex_acquire_nest() expects a pointer, pass the pointer.

Fixes: 12235da8c80a1 ("kernel/locking: Add context to ww_mutex_trylock()")
Signed-off-

kernel/locking: Use a pointer in ww_mutex_trylock().

mutex_acquire_nest() expects a pointer, pass the pointer.

Fixes: 12235da8c80a1 ("kernel/locking: Add context to ww_mutex_trylock()")
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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Revision tags: v5.15, v5.15-rc7, v5.15-rc6, v5.15-rc5, v5.15-rc4, v5.15-rc3, v5.15-rc2, v5.15-rc1
# 12235da8 09-Sep-2021 Maarten Lankhorst <[email protected]>

kernel/locking: Add context to ww_mutex_trylock()

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 l

kernel/locking: Add context to ww_mutex_trylock()

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 <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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Revision tags: v5.14, v5.14-rc7, v5.14-rc6
# f8635d50 15-Aug-2021 Peter Zijlstra <[email protected]>

locking/ww_mutex: Implement rtmutex based ww_mutex API functions

Add the actual ww_mutex API functions which replace the mutex based variant
on RT enabled kernels.

Signed-off-by: Peter Zijlstra (In

locking/ww_mutex: Implement rtmutex based ww_mutex API functions

Add the actual ww_mutex API functions which replace the mutex based variant
on RT enabled kernels.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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