[Ingo, thanks for the heads up about this ...]
Hi Ingo,
Today's linux-next merge of the sparseirq tree got a conflict in
arch/x86/xen/spinlock.c between commit
168d2f464ab9860f0d1e66cf1f9684973222f1c6 ("xen: save previous spinlock
when blocking") from the x86 tree and commit
fb6dc57946f9ebfeac546dd0698d9f065c191668 ("x86: move kstat_irqs from
kstat to irq_desc") from the sparseirq tree.
I fixed it up (see below) and can carry it.
--
Cheers,
Stephen Rothwell sfr@xxxxxxxxxxxxxxxx
http://www.canb.auug.org.au/~sfr/
diff --cc arch/x86/xen/spinlock.c
index d072823,5a48aba..0000000
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@@ -194,60 -73,24 +194,60 @@@ static noinline int xen_spin_lock_slow(
if (irq == -1)
return 0;
+ start = spin_time_start();
+
/* announce we're spinning */
- spinning_lock(xl);
+ prev = spinning_lock(xl);
+
+ flags = __raw_local_save_flags();
+ if (irq_enable) {
+ ADD_STATS(taken_slow_irqenable, 1);
+ raw_local_irq_enable();
+ }
+
+ ADD_STATS(taken_slow, 1);
+ ADD_STATS(taken_slow_nested, prev != NULL);
- /* clear pending */
- xen_clear_irq_pending(irq);
+ do {
+ /* clear pending */
+ xen_clear_irq_pending(irq);
+
+ /* check again make sure it didn't become free while
+ we weren't looking */
+ ret = xen_spin_trylock(lock);
+ if (ret) {
+ ADD_STATS(taken_slow_pickup, 1);
+
+ /*
+ * If we interrupted another spinlock while it
+ * was blocking, make sure it doesn't block
+ * without rechecking the lock.
+ */
+ if (prev != NULL)
+ xen_set_irq_pending(irq);
+ goto out;
+ }
- /* check again make sure it didn't become free while
- we weren't looking */
- ret = xen_spin_trylock(lock);
- if (ret)
- goto out;
+ /*
+ * Block until irq becomes pending. If we're
+ * interrupted at this point (after the trylock but
+ * before entering the block), then the nested lock
+ * handler guarantees that the irq will be left
+ * pending if there's any chance the lock became free;
+ * xen_poll_irq() returns immediately if the irq is
+ * pending.
+ */
+ xen_poll_irq(irq);
+ ADD_STATS(taken_slow_spurious, !xen_test_irq_pending(irq));
+ } while (!xen_test_irq_pending(irq)); /* check for spurious wakeups */
- kstat_this_cpu.irqs[irq]++;
- /* block until irq becomes pending */
- xen_poll_irq(irq);
+ kstat_irqs_this_cpu(irq_to_desc(irq))++;
out:
- unspinning_lock(xl);
+ raw_local_irq_restore(flags);
+ unspinning_lock(xl, prev);
+ spin_time_accum_blocked(start);
+
return ret;
}
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