From 28c515f40faba1cd1589dcc3f6f0fe3e2f5f6325 Mon Sep 17 00:00:00 2001 From: Alan Donovan Date: Fri, 2 May 2014 13:06:58 -0400 Subject: [PATCH] runtime: fix bug in GOTRACEBACK=crash causing suppression of core dumps. Because gotraceback is called early and often, its cache commits to the value of getenv("GOTRACEBACK") before getenv is even ready. So now we reset its cache once getenv becomes ready. Panicking programs now dump core again. LGTM=rsc R=rsc CC=golang-codereviews https://golang.org/cl/97800045 --- src/pkg/runtime/runtime.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/src/pkg/runtime/runtime.c b/src/pkg/runtime/runtime.c index 725c6d838e..3a4f7199ed 100644 --- a/src/pkg/runtime/runtime.c +++ b/src/pkg/runtime/runtime.c @@ -11,6 +11,13 @@ enum { maxround = sizeof(uintptr), }; +// Keep a cached value to make gotraceback fast, +// since we call it on every call to gentraceback. +// The cached value is a uint32 in which the low bit +// is the "crash" setting and the top 31 bits are the +// gotraceback value. +static uint32 traceback_cache = ~(uint32)0; + // The GOTRACEBACK environment variable controls the // behavior of a Go program that is crashing and exiting. // GOTRACEBACK=0 suppress all tracebacks @@ -20,12 +27,6 @@ enum { int32 runtime·gotraceback(bool *crash) { - // Keep a cached value to make gotraceback fast, - // since we call it on every call to gentraceback. - // The cached value is a uint32 in which the low bit - // is the "crash" setting and the top 31 bits are the - // gotraceback value. - static uint32 cache = ~(uint32)0; byte *p; uint32 x; @@ -33,7 +34,7 @@ runtime·gotraceback(bool *crash) *crash = false; if(m->traceback != 0) return m->traceback; - x = runtime·atomicload(&cache); + x = runtime·atomicload(&traceback_cache); if(x == ~(uint32)0) { p = runtime·getenv("GOTRACEBACK"); if(p == nil) @@ -44,7 +45,7 @@ runtime·gotraceback(bool *crash) x = (2<<1) | 1; else x = runtime·atoi(p)<<1; - runtime·atomicstore(&cache, x); + runtime·atomicstore(&traceback_cache, x); } if(crash != nil) *crash = x&1; @@ -137,6 +138,8 @@ runtime·goenvs_unix(void) syscall·envs.array = (byte*)s; syscall·envs.len = n; syscall·envs.cap = n; + + traceback_cache = ~(uint32)0; } int32 -- 2.50.0