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irq_work: Convert flags to atomic_t

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We need to convert flags to atomic_t in order to later fix an ordering
issue on atomic_cmpxchg() failure. This will allow us to use atomic_fetch_or().

Also clarify the nature of those flags.

[ mingo: Converted two more usage site the original patch missed. ]

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191108160858.31665-2-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Frederic Weisbecker
2019-11-08 17:08:55 +01:00
committed by Ingo Molnar
parent 31f4f5b495
commit 153bedbac2
5 changed files with 19 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/irq_work.c
+9 -9
View File
@@ -29,16 +29,16 @@ static DEFINE_PER_CPU(struct llist_head, lazy_list);
*/
static bool irq_work_claim(struct irq_work *work)
{
unsigned long flags, oflags, nflags;
int flags, oflags, nflags;
/*
* Start with our best wish as a premise but only trust any
* flag value after cmpxchg() result.
*/
flags = work->flags & ~IRQ_WORK_PENDING;
flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING;
for (;;) {
nflags = flags | IRQ_WORK_CLAIMED;
oflags = cmpxchg(&work->flags, flags, nflags);
oflags = atomic_cmpxchg(&work->flags, flags, nflags);
if (oflags == flags)
break;
if (oflags & IRQ_WORK_PENDING)
@@ -61,7 +61,7 @@ void __weak arch_irq_work_raise(void)
static void __irq_work_queue_local(struct irq_work *work)
{
/* If the work is "lazy", handle it from next tick if any */
if (work->flags & IRQ_WORK_LAZY) {
if (atomic_read(&work->flags) & IRQ_WORK_LAZY) {
if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
tick_nohz_tick_stopped())
arch_irq_work_raise();
@@ -143,7 +143,7 @@ static void irq_work_run_list(struct llist_head *list)
{
struct irq_work *work, *tmp;
struct llist_node *llnode;
unsigned long flags;
int flags;
BUG_ON(!irqs_disabled());
@@ -159,15 +159,15 @@ static void irq_work_run_list(struct llist_head *list)
* to claim that work don't rely on us to handle their data
* while we are in the middle of the func.
*/
flags = work->flags & ~IRQ_WORK_PENDING;
xchg(&work->flags, flags);
flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING;
atomic_xchg(&work->flags, flags);
work->func(work);
/*
* Clear the BUSY bit and return to the free state if
* no-one else claimed it meanwhile.
*/
(void)cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
(void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
}
}
@@ -199,7 +199,7 @@ void irq_work_sync(struct irq_work *work)
{
lockdep_assert_irqs_enabled();
while (work->flags & IRQ_WORK_BUSY)
while (atomic_read(&work->flags) & IRQ_WORK_BUSY)
cpu_relax();
}
EXPORT_SYMBOL_GPL(irq_work_sync);