net: don't use in_atomic() in gfp_any()
The problem is that in_atomic() will return false inside spinlocks if
CONFIG_PREEMPT=n. This will lead to deadlockable GFP_KERNEL allocations
from spinlocked regions.
Secondly, if CONFIG_PREEMPT=y, this bug solves itself because networking
will instead use GFP_ATOMIC from this callsite. Hence we won't get the
might_sleep() debugging warnings which would have informed us of the buggy
callsites.
Solve both these problems by switching to in_interrupt(). Now, if someone
runs a gfp_any() allocation from inside spinlock we will get the warning
if CONFIG_PREEMPT=y.
I reviewed all callsites and most of them were too complex for my little
brain and none of them documented their interface requirements. I have no
idea what this patch will do.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index 5a3a151..ce3b5b6 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1308,7 +1308,7 @@
static inline gfp_t gfp_any(void)
{
- return in_atomic() ? GFP_ATOMIC : GFP_KERNEL;
+ return in_softirq() ? GFP_ATOMIC : GFP_KERNEL;
}
static inline long sock_rcvtimeo(const struct sock *sk, int noblock)