Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 1/4] irq_work: Convert flags to atomic_t | Date | Fri, 8 Nov 2019 17:08:55 +0100 |
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We need to convert flags to atomic_t in order to later fix an ordering issue on cmpxchg() failure. This will allow us to use atomic_fetch_or(). Also that clarify the nature of those flags.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> --- include/linux/irq_work.h | 10 +++++++--- kernel/irq_work.c | 18 +++++++++--------- kernel/printk/printk.c | 2 +- 3 files changed, 17 insertions(+), 13 deletions(-)
diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h index b11fcdfd0770..02da997ad12c 100644 --- a/include/linux/irq_work.h +++ b/include/linux/irq_work.h @@ -22,7 +22,7 @@ #define IRQ_WORK_CLAIMED (IRQ_WORK_PENDING | IRQ_WORK_BUSY) struct irq_work { - unsigned long flags; + atomic_t flags; struct llist_node llnode; void (*func)(struct irq_work *); }; @@ -30,11 +30,15 @@ struct irq_work { static inline void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *)) { - work->flags = 0; + atomic_set(&work->flags, 0); work->func = func; } -#define DEFINE_IRQ_WORK(name, _f) struct irq_work name = { .func = (_f), } +#define DEFINE_IRQ_WORK(name, _f) struct irq_work name = { \ + .flags = ATOMIC_INIT(0), \ + .func = (_f) \ +} + bool irq_work_queue(struct irq_work *work); bool irq_work_queue_on(struct irq_work *work, int cpu); diff --git a/kernel/irq_work.c b/kernel/irq_work.c index d42acaf81886..df0dbf4d859b 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -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); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index ca65327a6de8..865727373a3b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2961,7 +2961,7 @@ static void wake_up_klogd_work_func(struct irq_work *irq_work) static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { .func = wake_up_klogd_work_func, - .flags = IRQ_WORK_LAZY, + .flags = ATOMIC_INIT(IRQ_WORK_LAZY), }; void wake_up_klogd(void) -- 2.23.0
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