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.
Regards
Neil
Signed-off-by: Neil Horman <[email protected]>
drivers/s390/net/lcs.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/drivers/s390/net/lcs.c
+++ b/drivers/s390/net/lcs.c
@@ -1729,11 +1729,13 @@ lcs_start_kernel_thread(struct lcs_card
{
LCS_DBF_TEXT(5, trace, "krnthrd");
if (lcs_do_start_thread(card, LCS_RECOVERY_THREAD))
- kernel_thread(lcs_recovery, (void *) card, SIGCHLD);
+ if (kernel_thread(lcs_recovery, (void *) card, SIGCHLD) < 0)
+ printk(KERN_WARNING "Could not start lcs recovery thread\n");
#ifdef CONFIG_IP_MULTICAST
if (lcs_do_start_thread(card, LCS_SET_MC_THREAD))
- kernel_thread(lcs_register_mc_addresses,
- (void *) card, SIGCHLD);
+ if (kernel_thread(lcs_register_mc_addresses,
+ (void *) card, SIGCHLD) < 0)
+ printk(KERN_WARNING "Could not start lcs mc thread\n");
#endif
}
-
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