tree d163be310654d08362c9f7b620bf8e4c46d0dca2
parent df91b8044dbe790c69c16058330f545be069cc1f
author Vladimir Stefanovic <vladimir.stefanovic@imgtec.com> 1493909129 +0200
committer Cherry Zhang <cherryyz@google.com> 1501075799 +0000

runtime/pprof: prevent a deadlock that SIGPROF might create on mips{,le}

64bit atomics on mips/mipsle are implemented using spinlocks. If SIGPROF
is received while the program is in the critical section, it will try to
write the sample using the same spinlock, creating a deadloop.
Prevent it by creating a counter of SIGPROFs during atomic64 and
postpone writing the sample(s) until called from elsewhere, with
pc set to _LostSIGPROFDuringAtomic64.

Added a test case, per Cherry's suggestion. Works around #20146.

Change-Id: Icff504180bae4ee83d78b19c0d9d6a80097087f9
Reviewed-on: https://go-review.googlesource.com/42652
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>