[KJ] audit return code handling for kernel_thread [7/11]

From: nhorman
Date: Fri Jul 28 2006 - 16:09:05 EST

Audit/Cleanup of kernel_thread calls, specifically checking of return codes.
Problems seemed to fall into 3 main categories:

1) callers of kernel_thread were inconsistent about meaning of a zero return
code. Some callers considered a zero return code to mean success, others took
it to mean failure. a zero return code, while not actually possible in the
current implementation, should be considered a success (pid 0 is/should be
valid). fixed all callers to treat zero return as success

2) caller of kernel_thread saved return code of kernel_thread for later use
without ever checking its value. Callers who did this tended to assume a
non-zero return was success, and would often wait for a completion queue to be
woken up, implying that an error (negative return code) from kernel_thread could
lead to deadlock. Repaired by checking return code at call time, and setting
saved return code to zero in the event of an error.

3) callers of kernel_thread never bothered to check the return code at all.
This can lead to seemingly unrelated errors later in execution. Fixed by
checking return code at call time and printing a warning message on failure.


Signed-off-by: Neil Horman <nhorman@xxxxxxxxxxxxx>

drivers/macintosh/mediabay.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/macintosh/mediabay.c
+++ b/drivers/macintosh/mediabay.c
@@ -699,7 +699,8 @@ static int __devinit media_bay_attach(st

/* Startup kernel thread */
if (i == 0)
- kernel_thread(media_bay_task, NULL, CLONE_KERNEL);
+ if (kernel_thread(media_bay_task, NULL, CLONE_KERNEL) < 0)
+ printk(KERN_WARNING "Could not start media bay task\n");

return 0;

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/