add core dump file name pattern option for cpu id

add core dump file name pattern option for cpu id

[Joshua Aas]

Normally core dumps can be blamed on a program itself. However, core
dumps can also be the result of faulty hardware. Tracking down what CPU
a failure occurred on usually requires that hardware be powered off
piece by piece until no core dumps occur (on big machines this can take
a long time). Another option is to run the test pinned to each CPU until
the core dump occurs, but this can also take a long time on big
machines. It would be very beneficial if the kernel was capable of
making the CPU ID of the CPU the core dump occurred on available
somehow. The following patch adds an option (%c) to the core dump file
naming pattern convention for putting the CPU ID into core dump file
names.

Signed-off-by: Josh Aas <josha@sgi.com>

-----------------------------------------------------------------
--- a/fs/exec.c	2004-07-13 14:32:24.000000000 -0500
+++ b/fs/exec.c	2004-07-15 13:16:17.000000000 -0500
@@ -1276,6 +1276,14 @@ void format_corename(char *corename, con
 					goto out;
 				out_ptr += rc;
 				break;
+			/* cpu id */
+			case 'c':
+				rc = snprintf(out_ptr, out_end - out_ptr,
+					      "%d", smp_processor_id());
+				if (rc > out_end - out_ptr)
+					goto out;
+				out_ptr += rc;
+				break;
 			default:
 				break;
 			}
-----------------------------------------------------------------

-- 
Josh Aas
Silicon Graphics, Inc. (SGI)
Linux System Software
651-683-3068

Re: add core dump file name pattern option for cpu id

[Josh Aas]

On Thu, 2004-07-15 at 15:14, Joshua Aas wrote:
> Normally core dumps can be blamed on a program itself. However, core
> dumps can also be the result of faulty hardware. Tracking down what CPU
> a failure occurred on usually requires that hardware be powered off
> piece by piece until no core dumps occur (on big machines this can take
> a long time). Another option is to run the test pinned to each CPU until
> the core dump occurs, but this can also take a long time on big
> machines. It would be very beneficial if the kernel was capable of
> making the CPU ID of the CPU the core dump occurred on available
> somehow. The following patch adds an option (%c) to the core dump file
> naming pattern convention for putting the CPU ID into core dump file
> names.
> 
> Signed-off-by: Josh Aas <josha@sgi.com>
> 
-----------------------------------------------------------------
--- a/fs/exec.c	2004-07-13 14:32:24.000000000 -0500
+++ b/fs/exec.c	2004-07-15 13:16:17.000000000 -0500
@@ -1276,6 +1276,14 @@ void format_corename(char *corename, con
 					goto out;
 				out_ptr += rc;
 				break;
+			/* cpu id */
+			case 'c':
+				rc = snprintf(out_ptr, out_end - out_ptr,
+					      "%d", smp_processor_id());
+				if (rc > out_end - out_ptr)
+					goto out;
+				out_ptr += rc;
+				break;
 			default:
 				break;
 			}
-----------------------------------------------------------------

Is there any reason this couldn't be taken into the kernel? I didn't get
any response at all and it seems to be a safe and useful patch. Any
feedback would be appreciated.

--
Josh Aas
Silicon Graphics, Inc. (SGI)
Linux System Software
651-683-3068