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Subject[PATCH] scsi: myrs: avoid stack overflow warning
Date
Putting a 1024 byte data structure on the stack is generally a bad idea.
On 32-bit systems, it also triggers a compile-time warning when building
with -Og:

drivers/scsi/myrs.c: In function 'myrs_get_ctlr_info':
drivers/scsi/myrs.c:212:1: error: the frame size of 1028 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

We only really need three members of the structure, so just read them
manually here instead of copying the entire structure.

Fixes: 77266186397c ("scsi: myrs: Add Mylex RAID controller (SCSI interface)")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/scsi/myrs.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/myrs.c b/drivers/scsi/myrs.c
index 0264a2e2bc19..b8d54ef8cf6d 100644
--- a/drivers/scsi/myrs.c
+++ b/drivers/scsi/myrs.c
@@ -163,9 +163,12 @@ static unsigned char myrs_get_ctlr_info(struct myrs_hba *cs)
dma_addr_t ctlr_info_addr;
union myrs_sgl *sgl;
unsigned char status;
- struct myrs_ctlr_info old;
+ unsigned short ldev_present, ldev_critical, ldev_offline;
+
+ ldev_present = cs->ctlr_info->ldev_present;
+ ldev_critical = cs->ctlr_info->ldev_critical;
+ ldev_offline = cs->ctlr_info->ldev_offline;

- memcpy(&old, cs->ctlr_info, sizeof(struct myrs_ctlr_info));
ctlr_info_addr = dma_map_single(&cs->pdev->dev, cs->ctlr_info,
sizeof(struct myrs_ctlr_info),
DMA_FROM_DEVICE);
@@ -198,9 +201,9 @@ static unsigned char myrs_get_ctlr_info(struct myrs_hba *cs)
cs->ctlr_info->rbld_active +
cs->ctlr_info->exp_active != 0)
cs->needs_update = true;
- if (cs->ctlr_info->ldev_present != old.ldev_present ||
- cs->ctlr_info->ldev_critical != old.ldev_critical ||
- cs->ctlr_info->ldev_offline != old.ldev_offline)
+ if (cs->ctlr_info->ldev_present != ldev_present ||
+ cs->ctlr_info->ldev_critical != ldev_critical ||
+ cs->ctlr_info->ldev_offline != ldev_offline)
shost_printk(KERN_INFO, cs->host,
"Logical drive count changes (%d/%d/%d)\n",
cs->ctlr_info->ldev_critical,
--
2.18.0
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