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runtime/trace: fix tracing of blocking system calls

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The placement and invocation of traceGoSysCall when using
entersyscallblock() instead of entersyscall() differs enough that the
TestTraceSymbolize test can fail on some platforms.

This change moves the invocation of traceGoSysCall for entersyscall() so
that the same number of "frames to skip" are present in the trace as when
entersyscallblock() is used ensuring system call traces remain identical
regardless of internal implementation choices.

Fixes golang/go#12056

Change-Id: I8361e91aa3708f5053f98263dfe9feb8c5d1d969
Reviewed-on: https://go-review.googlesource.com/13861
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
This commit is contained in:
Shawn Walker-Salas 2015-08-18 14:13:38 -07:00 committed by Dmitry Vyukov
parent 3d1f8c2379
commit 001a75a74c
2 changed files with 9 additions and 5 deletions
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12
src/runtime/proc1.go
View File

@ -1823,10 +1823,6 @@ func reentersyscall(pc, sp uintptr) {
// but can have inconsistent g->sched, do not let GC observe it. // but can have inconsistent g->sched, do not let GC observe it.
_g_.m.locks++ _g_.m.locks++
if trace.enabled {
systemstack(traceGoSysCall)
}
// Entersyscall must not call any function that might split/grow the stack. // Entersyscall must not call any function that might split/grow the stack.
// (See details in comment above.) // (See details in comment above.)
// Catch calls that might, by replacing the stack guard with something that // Catch calls that might, by replacing the stack guard with something that
@ -1846,6 +1842,14 @@ func reentersyscall(pc, sp uintptr) {
}) })
} }
if trace.enabled {
systemstack(traceGoSysCall)
// systemstack itself clobbers g.sched.{pc,sp} and we might
// need them later when the G is genuinely blocked in a
// syscall
save(pc, sp)
}
if atomicload(&sched.sysmonwait) != 0 { // TODO: fast atomic if atomicload(&sched.sysmonwait) != 0 { // TODO: fast atomic
systemstack(entersyscall_sysmon) systemstack(entersyscall_sysmon)
save(pc, sp) save(pc, sp)

2
src/runtime/trace.go
View File

@ -828,7 +828,7 @@ func traceGoUnpark(gp *g, skip int) {
} }
func traceGoSysCall() { func traceGoSysCall() {
traceEvent(traceEvGoSysCall, 4) traceEvent(traceEvGoSysCall, 1)
} }
func traceGoSysExit(seq uint64, ts int64) { func traceGoSysExit(seq uint64, ts int64) {