Your subject line is very tame. It should be the one line summary of
why we apply the patch, so it should read something like
hpsa: fix NULL deref in performant mode
On Thu, 2014-04-10 at 17:17 -0500, scameron@xxxxxxxxxxxxxxxxxx wrote:
> Without this, you'll see a null pointer dereference in
> hpsa_enter_performant_mode().
The description should be more comprehensible.
I'm clear that the use before initialisation is a bug ... I'm less clear
on why it causes an oops.
> Signed-off-by: Stephen M. Cameron <scameron@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/scsi/hpsa.c | 4 ++++
> 1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> index 8cf4a0c..ef4dfdd 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -7463,6 +7463,10 @@ static void hpsa_put_ctlr_into_performant_mode(struct ctlr_info *h)
> if (hpsa_simple_mode)
> return;
>
> + trans_support = readl(&(h->cfgtable->TransportSupport));
> + if (!(trans_support & PERFORMANT_MODE))
> + return;
> +
> /* Check for I/O accelerator mode support */
> if (trans_support & CFGTBL_Trans_io_accel1) {
> transMethod |= CFGTBL_Trans_io_accel1 |
Shouldn't you be moving this check from its previous location, rather
than adding a new one that makes the original obsolete?
James
---
diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 8cf4a0c..9a6e4a2 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -7463,6 +7463,10 @@ static void hpsa_put_ctlr_into_performant_mode(struct ctlr_info *h)
if (hpsa_simple_mode)
return;
+ trans_support = readl(&(h->cfgtable->TransportSupport));
+ if (!(trans_support & PERFORMANT_MODE))
+ return;
+
/* Check for I/O accelerator mode support */
if (trans_support & CFGTBL_Trans_io_accel1) {
transMethod |= CFGTBL_Trans_io_accel1 |
@@ -7479,10 +7483,6 @@ static void hpsa_put_ctlr_into_performant_mode(struct ctlr_info *h)
}
/* TODO, check that this next line h->nreply_queues is correct */
- trans_support = readl(&(h->cfgtable->TransportSupport));
- if (!(trans_support & PERFORMANT_MODE))
- return;
-
h->nreply_queues = h->msix_vector > 0 ? h->msix_vector : 1;
hpsa_get_max_perf_mode_cmds(h);
/* Performant mode ring buffer and supporting data structures */
--
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