diff options
| author | James Bottomley <James.Bottomley@HansenPartnership.com> | 2025-03-27 10:06:10 -0400 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-04-07 09:37:16 +0200 |
| commit | 559b3bbfa978ce3b23dc9c52d09a0eddca52c439 (patch) | |
| tree | 1489f8567bbb6a1fceaf01f1a963bb394ab0a07d /kernel | |
| parent | 0af2f6be1b4281385b618cb86ad946eded089ac8 (diff) | |
locking/percpu-rwsem: add freezable alternative to down_read
Percpu-rwsems are used for superblock locking. However, we know the
read percpu-rwsem we take for sb_start_write() on a frozen filesystem
needs not to inhibit system from suspending or hibernating. That
means it needs to wait with TASK_UNINTERRUPTIBLE | TASK_FREEZABLE.
Introduce a new percpu_down_read_freezable() that allows us to control
whether TASK_FREEZABLE is added to the wait flags.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Link: https://lore.kernel.org/r/20250327140613.25178-2-James.Bottomley@HansenPartnership.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/locking/percpu-rwsem.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index d6964fc29f51..ef234469baac 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -138,7 +138,8 @@ static int percpu_rwsem_wake_function(struct wait_queue_entry *wq_entry, return !reader; /* wake (readers until) 1 writer */ } -static void percpu_rwsem_wait(struct percpu_rw_semaphore *sem, bool reader) +static void percpu_rwsem_wait(struct percpu_rw_semaphore *sem, bool reader, + bool freeze) { DEFINE_WAIT_FUNC(wq_entry, percpu_rwsem_wake_function); bool wait; @@ -156,7 +157,8 @@ static void percpu_rwsem_wait(struct percpu_rw_semaphore *sem, bool reader) spin_unlock_irq(&sem->waiters.lock); while (wait) { - set_current_state(TASK_UNINTERRUPTIBLE); + set_current_state(TASK_UNINTERRUPTIBLE | + (freeze ? TASK_FREEZABLE : 0)); if (!smp_load_acquire(&wq_entry.private)) break; schedule(); @@ -164,7 +166,8 @@ static void percpu_rwsem_wait(struct percpu_rw_semaphore *sem, bool reader) __set_current_state(TASK_RUNNING); } -bool __sched __percpu_down_read(struct percpu_rw_semaphore *sem, bool try) +bool __sched __percpu_down_read(struct percpu_rw_semaphore *sem, bool try, + bool freeze) { if (__percpu_down_read_trylock(sem)) return true; @@ -174,7 +177,7 @@ bool __sched __percpu_down_read(struct percpu_rw_semaphore *sem, bool try) trace_contention_begin(sem, LCB_F_PERCPU | LCB_F_READ); preempt_enable(); - percpu_rwsem_wait(sem, /* .reader = */ true); + percpu_rwsem_wait(sem, /* .reader = */ true, freeze); preempt_disable(); trace_contention_end(sem, 0); @@ -237,7 +240,7 @@ void __sched percpu_down_write(struct percpu_rw_semaphore *sem) */ if (!__percpu_down_write_trylock(sem)) { trace_contention_begin(sem, LCB_F_PERCPU | LCB_F_WRITE); - percpu_rwsem_wait(sem, /* .reader = */ false); + percpu_rwsem_wait(sem, /* .reader = */ false, false); contended = true; } |