diff options
| author | Alexander Bluhm <bluhm@cvs.openbsd.org> | 2021-06-10 12:33:49 +0000 |
|---|---|---|
| committer | Alexander Bluhm <bluhm@cvs.openbsd.org> | 2021-06-10 12:33:49 +0000 |
| commit | b3394658bdf95c4bcbc4b1a82060996a79f3ae38 (patch) | |
| tree | 3cdf800dc4139255da433100e4d56d0f90907dbb /sys | |
| parent | 8c9eef24e1188e359ff84f55b3ca0402108d7833 (diff) | |
Prevent interleaved stack traces in ddb from multiple CPUs. Check
atomically which CPU is currently tracing.
OK cheloha@
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/ddb/db_output.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/sys/ddb/db_output.c b/sys/ddb/db_output.c index 3aa2c6a8657..d6abed2745b 100644 --- a/sys/ddb/db_output.c +++ b/sys/ddb/db_output.c @@ -1,4 +1,4 @@ -/* $OpenBSD: db_output.c,v 1.36 2021/02/09 14:37:13 jcs Exp $ */ +/* $OpenBSD: db_output.c,v 1.37 2021/06/10 12:33:48 bluhm Exp $ */ /* $NetBSD: db_output.c,v 1.13 1996/04/01 17:27:14 christos Exp $ */ /* @@ -31,6 +31,7 @@ * Printf and character output for debugger. */ #include <sys/param.h> +#include <sys/atomic.h> #include <sys/stdarg.h> #include <sys/systm.h> #include <sys/stacktrace.h> @@ -224,19 +225,24 @@ db_format(char *buf, size_t bufsize, long val, int format, int alt, int width) void db_stack_dump(void) { - static volatile int intrace; + static struct cpu_info *intrace = NULL; + struct cpu_info *tracing, *ci = curcpu(); - if (intrace) { - printf("Faulted in traceback, aborting...\n"); + tracing = atomic_cas_ptr(&intrace, NULL, ci); + if (tracing != NULL) { + if (tracing == ci) + printf("Faulted in traceback, aborting...\n"); + else + printf("Parallel traceback, suppressed...\n"); return; } - intrace = 1; printf("Starting stack trace...\n"); db_stack_trace_print((db_expr_t)__builtin_frame_address(0), 1, 256 /* low limit */, "", printf); printf("End of stack trace.\n"); - intrace = 0; + membar_producer(); + intrace = NULL; } void |