scsi: pm8001: Avoid -Wrestrict warning

On some configurations, gcc warns about overlapping source and destination
arguments to snprintf:

drivers/scsi/pm8001/pm8001_init.c: In function 'pm8001_request_msix':
drivers/scsi/pm8001/pm8001_init.c:977:3: error: 'snprintf' argument 4 may overlap destination object 'pm8001_ha' [-Werror=restrict]
  977 |   snprintf(drvname, len, "%s-%d", pm8001_ha->name, i);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/scsi/pm8001/pm8001_init.c:962:56: note: destination object referenced by 'restrict'-qualified argument 1 was declared here
  962 | static u32 pm8001_request_msix(struct pm8001_hba_info *pm8001_ha)
      |                                ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~

I first assumed this was a gcc bug, as that should not happen, but a
reduced test case makes it clear that this happens when the loop counter is
not bounded by the array size.

Help the compiler out by adding an explicit limit here to make the code
slightly more robust and avoid the warning.

Link: https://godbolt.org/z/6T1qPM
Link: https://lore.kernel.org/r/20210323125458.1825564-1-arnd@kernel.org
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/pm8001/pm8001_init.c b/drivers/scsi/pm8001/pm8001_init.c
index bbb6b23aa6b1cb47a537920fb7f02ad4ba7fc166..0f7b3fffb393e3ed1b5a72532cd4bf806bcf59a6 100644 (file)
--- a/drivers/scsi/pm8001/pm8001_init.c
+++ b/drivers/scsi/pm8001/pm8001_init.c
@@ -963,6 +963,7 @@ static u32 pm8001_request_msix(struct pm8001_hba_info *pm8001_ha)
 {
        u32 i = 0, j = 0;
        int flag = 0, rc = 0;
+       int nr_irqs = pm8001_ha->number_of_intr;
 
        if (pm8001_ha->chip_id != chip_8001)
                flag &= ~IRQF_SHARED;
@@ -971,7 +972,10 @@ static u32 pm8001_request_msix(struct pm8001_hba_info *pm8001_ha)
                   "pci_enable_msix request number of intr %d\n",
                   pm8001_ha->number_of_intr);
 
-       for (i = 0; i < pm8001_ha->number_of_intr; i++) {
+       if (nr_irqs > ARRAY_SIZE(pm8001_ha->intr_drvname))
+               nr_irqs = ARRAY_SIZE(pm8001_ha->intr_drvname);
+
+       for (i = 0; i < nr_irqs; i++) {
                snprintf(pm8001_ha->intr_drvname[i],
                        sizeof(pm8001_ha->intr_drvname[0]),
                        "%s-%d", pm8001_ha->name, i);