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

From: nhorman
Date: Fri Jul 28 2006 - 16:08:36 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>

arch/ia64/sn/kernel/xpc_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/ia64/sn/kernel/xpc_main.c
+++ b/arch/ia64/sn/kernel/xpc_main.c
@@ -583,7 +583,7 @@ xpc_activate_partition(struct xpc_partit

pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);

- if (unlikely(pid <= 0)) {
+ if (unlikely(pid < 0)) {
spin_lock_irqsave(&part->act_lock, irq_flags);
part->act_state = XPC_P_INACTIVE;
XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
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