2018-01-16 09:36:49

by Arnd Bergmann

Subject: [PATCH] staging: lustre: lnet: avoid uninitialized return value

gcc warns that the latest workqueue change leads to returning an
uninitialized variable:

drivers/staging/lustre/lnet/selftest/module.c: In function 'lnet_selftest_init':
drivers/staging/lustre/lnet/selftest/module.c:98:10: error: 'rc' may be used uninitialized in this function [-Werror=maybe-uninitialized]

A failure from alloc_ordered_workqueue() tends to indicate an
out-of-memory condition, so return -ENOMEM in both cases.
The second error path was a preexisting bug, where we always
returned zero after a kvmalloc_array() failure.

Fixes: 6106c0f82481 ("staging: lustre: lnet: convert selftest to use workqueues")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/staging/lustre/lnet/selftest/module.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/lustre/lnet/selftest/module.c b/drivers/staging/lustre/lnet/selftest/module.c
index aa6bfd5baf2f..c8d999e64f28 100644
--- a/drivers/staging/lustre/lnet/selftest/module.c
+++ b/drivers/staging/lustre/lnet/selftest/module.c
@@ -95,15 +95,17 @@ lnet_selftest_init(void)
lst_serial_wq = alloc_ordered_workqueue("lst_s", 0);
if (!lst_serial_wq) {
CERROR("Failed to create serial WI scheduler for LST\n");
- return rc;
+ return -ENOMEM;
}
lst_init_step = LST_INIT_WI_SERIAL;

nscheds = cfs_cpt_number(lnet_cpt_table());
lst_test_wq = kvmalloc_array(nscheds, sizeof(lst_test_wq[0]),
GFP_KERNEL | __GFP_ZERO);
- if (!lst_test_wq)
+ if (!lst_test_wq) {
+ rc = -ENOMEM;
goto error;
+ }

lst_init_step = LST_INIT_WI_TEST;
for (i = 0; i < nscheds; i++) {
@@ -116,6 +118,7 @@ lnet_selftest_init(void)
if (!lst_test_wq[i]) {
CWARN("Failed to create CPU partition affinity WI scheduler %d for LST\n",
i);
+ rc = -ENOMEM;
goto error;
}
attrs.nice = 0;
--
2.9.0

2018-01-17 16:06:51

by James Simmons

Subject: Re: [PATCH] staging: lustre: lnet: avoid uninitialized return value

> gcc warns that the latest workqueue change leads to returning an
> uninitialized variable:
>
> drivers/staging/lustre/lnet/selftest/module.c: In function 'lnet_selftest_init':
> drivers/staging/lustre/lnet/selftest/module.c:98:10: error: 'rc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> A failure from alloc_ordered_workqueue() tends to indicate an
> out-of-memory condition, so return -ENOMEM in both cases.
> The second error path was a preexisting bug, where we always
> returned zero after a kvmalloc_array() failure.

Reviewed-by: James Simmons <[email protected]>

> Fixes: 6106c0f82481 ("staging: lustre: lnet: convert selftest to use workqueues")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/staging/lustre/lnet/selftest/module.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/lustre/lnet/selftest/module.c b/drivers/staging/lustre/lnet/selftest/module.c
> index aa6bfd5baf2f..c8d999e64f28 100644
> --- a/drivers/staging/lustre/lnet/selftest/module.c
> +++ b/drivers/staging/lustre/lnet/selftest/module.c
> @@ -95,15 +95,17 @@ lnet_selftest_init(void)
> lst_serial_wq = alloc_ordered_workqueue("lst_s", 0);
> if (!lst_serial_wq) {
> CERROR("Failed to create serial WI scheduler for LST\n");
> - return rc;
> + return -ENOMEM;
> }
> lst_init_step = LST_INIT_WI_SERIAL;
>
> nscheds = cfs_cpt_number(lnet_cpt_table());
> lst_test_wq = kvmalloc_array(nscheds, sizeof(lst_test_wq[0]),
> GFP_KERNEL | __GFP_ZERO);
> - if (!lst_test_wq)
> + if (!lst_test_wq) {
> + rc = -ENOMEM;
> goto error;
> + }
>
> lst_init_step = LST_INIT_WI_TEST;
> for (i = 0; i < nscheds; i++) {
> @@ -116,6 +118,7 @@ lnet_selftest_init(void)
> if (!lst_test_wq[i]) {
> CWARN("Failed to create CPU partition affinity WI scheduler %d for LST\n",
> i);
> + rc = -ENOMEM;
> goto error;
> }
> attrs.nice = 0;
> --
> 2.9.0
>
>