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authorFrederic Weisbecker <fweisbec@gmail.com>2013-09-05 16:14:00 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2013-10-01 12:53:27 +0200
commit0bed698a334766ed07bacd6cb33f0228003a7f61 (patch)
tree476b852529e75b8d9d3c6e8bedd21468cb1e8f82
parent5d60d3e7c08a46643e902e39d9743cf394382151 (diff)
irq: Justify the various softirq stack choices
For clarity, comment the various stack choices for softirqs processing, whether we execute them from ksoftirqd or local_irq_enable() calls. Their use on irq_exit() is already commented. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@au1.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Mackerras <paulus@au1.ibm.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: James E.J. Bottomley <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--kernel/softirq.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 9f8092b82a94..2b4328ea769f 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -170,8 +170,13 @@ static inline void _local_bh_enable_ip(unsigned long ip)
*/
sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1);
- if (unlikely(!in_interrupt() && local_softirq_pending()))
+ if (unlikely(!in_interrupt() && local_softirq_pending())) {
+ /*
+ * Run softirq if any pending. And do it in its own stack
+ * as we may be calling this deep in a task call stack already.
+ */
do_softirq();
+ }
dec_preempt_count();
#ifdef CONFIG_TRACE_IRQFLAGS
@@ -769,6 +774,10 @@ static void run_ksoftirqd(unsigned int cpu)
{
local_irq_disable();
if (local_softirq_pending()) {
+ /*
+ * We can safely run softirq on inline stack, as we are not deep
+ * in the task stack here.
+ */
__do_softirq();
rcu_note_context_switch(cpu);
local_irq_enable();