[PATCH net-next] cxgb4: remove redundant NULL check

Fix below warnings reported by coccicheck:
./drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c:323:3-9: WARNING:
NULL check before some freeing functions is not needed.
./drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c:3554:2-8: WARNING:
NULL check before some freeing functions is not needed.
./drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c:157:2-7: WARNING:
NULL check before some freeing functions is not needed.
./drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c:525:3-9: WARNING:
NULL check before some freeing functions is not needed.

Reported-by: Abaci Robot <redacted>
Signed-off-by: Yang Li <redacted>
---
 drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c     | 3 +--
 drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c    | 3 +--
 drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c  | 3 +--
 drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c | 6 ++----
 4 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c b/drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c
index ce28820..12fcf84 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c

@@ -323,8 +323,7 @@ void t4_cleanup_clip_tbl(struct adapter *adap)
 	struct clip_tbl *ctbl = adap->clipt;
 
 	if (ctbl) {
-		if (ctbl->cl_list)
-			kvfree(ctbl->cl_list);
+		kvfree(ctbl->cl_list);
 		kvfree(ctbl);
 	}
 }

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c b/drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c
index 75474f8..94eb8a6 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c

@@ -3554,8 +3554,7 @@ int cudbg_collect_qdesc(struct cudbg_init *pdbg_init,
 	}
 
 out_free:
-	if (data)
-		kvfree(data);
+	kvfree(data);
 
 #undef QDESC_GET_FLQ
 #undef QDESC_GET_RXQ

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c
index 77648e4..dd66b24 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c

@@ -157,8 +157,7 @@ static int cudbg_alloc_compress_buff(struct cudbg_init *pdbg_init)
 
 static void cudbg_free_compress_buff(struct cudbg_init *pdbg_init)
 {
-	if (pdbg_init->compress_buff)
-		vfree(pdbg_init->compress_buff);
+	vfree(pdbg_init->compress_buff);
 }
 
 int cxgb4_cudbg_collect(struct adapter *adap, void *buf, u32 *buf_size,

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c
index dede025..97a811f 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c

@@ -525,12 +525,10 @@ struct cxgb4_tc_u32_table *cxgb4_init_tc_u32(struct adapter *adap)
 	for (i = 0; i < t->size; i++) {
 		struct cxgb4_link *link = &t->table[i];
 
-		if (link->tid_map)
-			kvfree(link->tid_map);
+		kvfree(link->tid_map);
 	}
 
-	if (t)
-		kvfree(t);
+	kvfree(t);
 
 	return NULL;
 }

-- 
1.8.3.1

On Tuesday, January 01/26/21, 2021 at 10:50:13 +0800, Yang Li wrote:

NAK. The above check is necessary.

pdbg_init->compress_buff may be NULL when Zlib is unavailable or when
pdbg_init->compress_buff allocation fails, in which case we ignore error
and continue without compression. Check is necessary before calling
vfree().

The above change is wrong. NAK.

If the call to link->tid_map = kvcalloc() above fails, it still
goes ahead and calls kvfree(link->tid_map) even for failed cases, which is
wrong. Check is necessary before calling kvfree().

 	}
 
-	if (t)
-		kvfree(t);
+	kvfree(t);
 
 	return NULL;
 }
-- 
1.8.3.1

On Wed, 27 Jan 2021 12:04:27 +0530 Raju Rangoju wrote:

On Tuesday, January 01/26/21, 2021 at 10:50:13 +0800, Yang Li wrote:

quoted

Fix below warnings reported by coccicheck:
./drivers/net/ethernet/chelsio/cxgb4/clip_tbl.c:323:3-9: WARNING:
NULL check before some freeing functions is not needed.
./drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c:3554:2-8: WARNING:
NULL check before some freeing functions is not needed.
./drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c:157:2-7: WARNING:
NULL check before some freeing functions is not needed.
./drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c:525:3-9: WARNING:
NULL check before some freeing functions is not needed.

Reported-by: Abaci Robot <redacted>
Signed-off-by: Yang Li <redacted>

quoted

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c
index 77648e4..dd66b24 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_cudbg.c

@@ -157,8 +157,7 @@ static int cudbg_alloc_compress_buff(struct cudbg_init *pdbg_init)
 
 static void cudbg_free_compress_buff(struct cudbg_init *pdbg_init)
 {
-	if (pdbg_init->compress_buff)  

NAK. The above check is necessary.

pdbg_init->compress_buff may be NULL when Zlib is unavailable or when
pdbg_init->compress_buff allocation fails, in which case we ignore error
and continue without compression. Check is necessary before calling
vfree().

Thanks taking a look! The point is that vfree() kfree() etc. all can be
fed NULL in which case they are a nop. E.g.:

/**
 * vfree - Release memory allocated by vmalloc()
 * @addr:  Memory base address
 *
 * Free the virtually continuous memory area starting at @addr, as obtained
 * from one of the vmalloc() family of APIs.  This will usually also free the
 * physical memory underlying the virtual allocation, but that memory is
 * reference counted, so it will not be freed until the last user goes away.
 *
   vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

* If @addr is NULL, no operation is performed. <=

   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 *
 * Context:
 * May sleep if called *not* from interrupt context.
 * Must not be called in NMI context (strictly speaking, it could be
 * if we have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
 * conventions for vfree() arch-depenedent would be a really bad idea).
 */

I don't think there is any advanced static analysis going on here if
that's what you assumed.

Yang, please respin, and explain in the patch message why removing
those conditions is safe.