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SubjectRe: [PATCH] staging:lustre: Prevent duplicate CT registrations
On Fri, Oct 23, 2015 at 03:59:14PM -0400, James Simmons wrote:
> diff --git a/drivers/staging/lustre/lustre/lmv/lmv_obd.c b/drivers/staging/lustre/lustre/lmv/lmv_obd.c
> index 635a93c..d6d70d8 100644
> --- a/drivers/staging/lustre/lustre/lmv/lmv_obd.c
> +++ b/drivers/staging/lustre/lustre/lmv/lmv_obd.c
> @@ -794,7 +794,9 @@ static void lmv_hsm_req_build(struct lmv_obd *lmv,
> static int lmv_hsm_ct_unregister(struct lmv_obd *lmv, unsigned int cmd, int len,
> struct lustre_kernelcomm *lk, void *uarg)
> {
> - int i, rc = 0;
> + struct kkuc_ct_data *kcd = NULL;
> + int rc = 0;
> + __u32 i;

We have been introducing a lot of new __u32 types here and I just
assumed there was a reason for it but this one is clearly wrong. The
new code implies that ->ld_tgt_count can overflow INT_MAX which is not
true and that this is code shared with userspace which might be true but
it's not described in the changelog. Is this a static checker fix?
Stop using that broken static checker, because the correct type here is
int.

Anyway, stop making gratuitous unrelated changes (like the white space
changes to local declarations). I feel like I have held off commenting
on this for a while and shown great restraint. :P

> - rc = libcfs_kkuc_group_rem(lk->lk_uid, lk->lk_group);
> + rc = libcfs_kkuc_group_rem(lk->lk_uid, lk->lk_group, (void**)&kcd);
> + if (kcd != NULL)
> + kfree(kcd);

NULL check not needed.

> +
> return rc;
> }
>
> static int lmv_hsm_ct_register(struct lmv_obd *lmv, unsigned int cmd, int len,
> struct lustre_kernelcomm *lk, void *uarg)
> {
> - struct file *filp;
> - int i, j, err;
> - int rc = 0;
> - bool any_set = false;
> + struct file *filp;
> + __u32 i, j;
> + int err, rc = 0;
> + bool any_set = false;
> + struct kkuc_ct_data *kcd;
>
> /* All or nothing: try to register to all MDS.
> * In case of failure, unregister from previous MDS,
> @@ -854,12 +860,25 @@ static int lmv_hsm_ct_register(struct lmv_obd *lmv, unsigned int cmd, int len,
>
> /* at least one registration done, with no failure */
> filp = fget(lk->lk_wfd);
> - if (filp == NULL) {
> + if (filp == NULL)
> return -EBADF;
> - }
> - rc = libcfs_kkuc_group_add(filp, lk->lk_uid, lk->lk_group, lk->lk_data);
> - if (rc != 0 && filp != NULL)
> +
> + kcd = kzalloc(sizeof(*kcd), GFP_NOFS);
> + if (kcd == NULL) {
> fput(filp);
> + return -ENOMEM;
> + }
> + kcd->kcd_magic = KKUC_CT_DATA_MAGIC;
> + kcd->kcd_uuid = lmv->cluuid;
> + kcd->kcd_archive = lk->lk_data;
> +
> + rc = libcfs_kkuc_group_add(filp, lk->lk_uid, lk->lk_group, kcd);
> + if (rc != 0) {

These double negatives are a pet peev of mine. "if (rc) {" Comparing
with zero like this is idiomatic when you're talking about the number
zero or strcmp(). Can we use a goto for unwinding? goto free_kcd;

> + if (filp != NULL)

The earlier NULL check means this can't happen.

> + fput(filp);
> + kfree(kcd);
> + }
> +
> return rc;

return 0;

free_kcd:
kfree(kcd);
put_filp:
fput(filp);

return rc;

regards,
dan carpenter



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