[KJ] audit return code handling for kernel_thread [10/11]

From: nhorman
Date: Fri Jul 28 2006 - 16:07:43 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/therm_pm72.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/macintosh/therm_pm72.c
+++ b/drivers/macintosh/therm_pm72.c
@@ -1769,6 +1769,10 @@ static void start_control_loops(void)

ctrl_task = kernel_thread(main_control_loop, NULL, SIGCHLD | CLONE_KERNEL);
+ if (ctrl_task < 0) {
+ printk(KERN_CRIT "could not start control thread\n");
+ ctrl_task = 0;
+ }

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