irq_work: Convert flags to atomic_t
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>
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index 052580c..4d31284 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -289,7 +289,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
if (in_nmi()) {
work = this_cpu_ptr(&up_read_work);
- if (work->irq_work.flags & IRQ_WORK_BUSY)
+ if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY)
/* cannot queue more up_read, fallback */
irq_work_busy = true;
}
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index d42acaf..df0dbf4 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 ca65327..8657273 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)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 44bd08f..ff467a4 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -660,7 +660,7 @@ BPF_CALL_1(bpf_send_signal, u32, sig)
return -EINVAL;
work = this_cpu_ptr(&send_signal_work);
- if (work->irq_work.flags & IRQ_WORK_BUSY)
+ if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY)
return -EBUSY;
/* Add the current task, which is the target of sending signal,