scsi: lpfc: Avoid usage of list iterator variable after loop

[ Upstream commit 2850b23e9f9ae3696e472d2883ea1b43aafa884e ]

If the &epd_pool->list is empty when executing
lpfc_get_io_buf_from_expedite_pool() the function would return an invalid
pointer. Even in the case if the list is guaranteed to be populated, the
iterator variable should not be used after the loop to be more robust for
future changes.

Linus proposed to avoid any use of the list iterator variable after the
loop, in the attempt to move the list iterator variable declaration into
the macro to avoid any potential misuse after the loop [1].

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/
Signed-off-by: Jakob Koschel <jkl820.git@gmail.com>
Link: https://lore.kernel.org/r/20230301-scsi-lpfc-avoid-list-iterator-after-loop-v1-1-325578ae7561@gmail.com
Reviewed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 1f1d346adc038798f171bbe2b3de3fcb1a3a3ba1..30bc72324f068a7fbb1fb2f107b07c1304e8c057 100644 (file)
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -22166,20 +22166,20 @@ lpfc_get_io_buf_from_private_pool(struct lpfc_hba *phba,
 static struct lpfc_io_buf *
 lpfc_get_io_buf_from_expedite_pool(struct lpfc_hba *phba)
 {
-       struct lpfc_io_buf *lpfc_ncmd;
+       struct lpfc_io_buf *lpfc_ncmd = NULL, *iter;
        struct lpfc_io_buf *lpfc_ncmd_next;
        unsigned long iflag;
        struct lpfc_epd_pool *epd_pool;
 
        epd_pool = &phba->epd_pool;
-       lpfc_ncmd = NULL;
 
        spin_lock_irqsave(&epd_pool->lock, iflag);
        if (epd_pool->count > 0) {
-               list_for_each_entry_safe(lpfc_ncmd, lpfc_ncmd_next,
+               list_for_each_entry_safe(iter, lpfc_ncmd_next,
                                         &epd_pool->list, list) {
-                       list_del(&lpfc_ncmd->list);
+                       list_del(&iter->list);
                        epd_pool->count--;
+                       lpfc_ncmd = iter;
                        break;
                }
        }