| Message ID | 20230508020120.218494-3-rmclure@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc: KCSAN fix warnings and mark accesses | expand |
On Mon May 8, 2023 at 12:01 PM AEST, Rohan McLure wrote: > The powerpc implemenation of qspinlocks will both poll and spin on the > bitlock guarding a qnode. Mark these accesses with READ_ONCE to convey > to KCSAN that polling is intentional here. Yeah, and obviously pairs with the WRITE_ONCE so comment isn't really necessary. Reviewed-by: Nicholas Piggin <npiggin@gmail.com> > > Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> > --- > arch/powerpc/lib/qspinlock.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/lib/qspinlock.c b/arch/powerpc/lib/qspinlock.c > index 9cf93963772b..579290d55abf 100644 > --- a/arch/powerpc/lib/qspinlock.c > +++ b/arch/powerpc/lib/qspinlock.c > @@ -435,7 +435,7 @@ static __always_inline bool yield_to_prev(struct qspinlock *lock, struct qnode * > > smp_rmb(); /* See __yield_to_locked_owner comment */ > > - if (node->locked) { > + if (READ_ONCE(node->locked)) { > yield_to_preempted(prev_cpu, yield_count); > spin_begin(); > return preempted; > @@ -584,7 +584,7 @@ static __always_inline void queued_spin_lock_mcs_queue(struct qspinlock *lock, b > > /* Wait for mcs node lock to be released */ > spin_begin(); > - while (node->locked) { > + while (READ_ONCE(node->locked)) { > spec_barrier(); > > if (yield_to_prev(lock, node, old, paravirt)) > -- > 2.37.2
diff --git a/arch/powerpc/lib/qspinlock.c b/arch/powerpc/lib/qspinlock.c index 9cf93963772b..579290d55abf 100644 --- a/arch/powerpc/lib/qspinlock.c +++ b/arch/powerpc/lib/qspinlock.c @@ -435,7 +435,7 @@ static __always_inline bool yield_to_prev(struct qspinlock *lock, struct qnode * smp_rmb(); /* See __yield_to_locked_owner comment */ - if (node->locked) { + if (READ_ONCE(node->locked)) { yield_to_preempted(prev_cpu, yield_count); spin_begin(); return preempted; @@ -584,7 +584,7 @@ static __always_inline void queued_spin_lock_mcs_queue(struct qspinlock *lock, b /* Wait for mcs node lock to be released */ spin_begin(); - while (node->locked) { + while (READ_ONCE(node->locked)) { spec_barrier(); if (yield_to_prev(lock, node, old, paravirt))
The powerpc implemenation of qspinlocks will both poll and spin on the bitlock guarding a qnode. Mark these accesses with READ_ONCE to convey to KCSAN that polling is intentional here. Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> --- arch/powerpc/lib/qspinlock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)