From 6623b0217d0c9bed80bfa43b778ce1c0eb03b497 Mon Sep 17 00:00:00 2001 From: Uros Bizjak Date: Sun, 21 Jul 2024 18:45:41 +0200 Subject: [PATCH 1/2] locking/pvqspinlock: Correct the type of "old" variable in pv_kick_node() "enum vcpu_state" is not compatible with "u8" type for all targets, resulting in: error: initialization of 'u8 *' {aka 'unsigned char *'} from incompatible pointer type 'enum vcpu_state *' for LoongArch. Correct the type of "old" variable to "u8". Fixes: fea0e1820b51 ("locking/pvqspinlock: Use try_cmpxchg() in qspinlock_paravirt.h") Closes: https://lore.kernel.org/lkml/20240719024010.3296488-1-maobibo@loongson.cn/ Reported-by: Bibo Mao Signed-off-by: Uros Bizjak Signed-off-by: Peter Zijlstra (Intel) Acked-by: Waiman Long Link: https://lore.kernel.org/r/20240721164552.50175-1-ubizjak@gmail.com --- kernel/locking/qspinlock_paravirt.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index f5a36e67b593..ac2e22502741 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -357,7 +357,7 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev) static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node) { struct pv_node *pn = (struct pv_node *)node; - enum vcpu_state old = vcpu_halted; + u8 old = vcpu_halted; /* * If the vCPU is indeed halted, advance its state to match that of * pv_wait_node(). If OTOH this fails, the vCPU was running and will From 224fa3552029a3d14bec7acf72ded8171d551b88 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 31 Jul 2024 12:43:21 +0200 Subject: [PATCH 2/2] jump_label: Fix the fix, brown paper bags galore Per the example of: !atomic_cmpxchg(&key->enabled, 0, 1) the inverse was written as: atomic_cmpxchg(&key->enabled, 1, 0) except of course, that while !old is only true for old == 0, old is true for everything except old == 0. Fix it to read: atomic_cmpxchg(&key->enabled, 1, 0) == 1 such that only the 1->0 transition returns true and goes on to disable the keys. Fixes: 83ab38ef0a0b ("jump_label: Fix concurrency issues in static_key_slow_dec()") Reported-by: Darrick J. Wong Signed-off-by: Peter Zijlstra (Intel) Tested-by: Darrick J. Wong Link: https://lkml.kernel.org/r/20240731105557.GY33588@noisy.programming.kicks-ass.net --- kernel/jump_label.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 4ad5ed8adf96..6dc76b590703 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -236,7 +236,7 @@ void static_key_disable_cpuslocked(struct static_key *key) } jump_label_lock(); - if (atomic_cmpxchg(&key->enabled, 1, 0)) + if (atomic_cmpxchg(&key->enabled, 1, 0) == 1) jump_label_update(key); jump_label_unlock(); } @@ -289,7 +289,7 @@ static void __static_key_slow_dec_cpuslocked(struct static_key *key) return; guard(mutex)(&jump_label_mutex); - if (atomic_cmpxchg(&key->enabled, 1, 0)) + if (atomic_cmpxchg(&key->enabled, 1, 0) == 1) jump_label_update(key); else WARN_ON_ONCE(!static_key_slow_try_dec(key));