* [PATCH net-next] cxgb4: remove redundant NULL check
@ 2021-01-26 2:50 Yang Li
2021-01-27 6:34 ` Raju Rangoju
0 siblings, 1 reply; 3+ messages in thread
From: Yang Li @ 2021-01-26 2:50 UTC (permalink / raw)
To: kuba; +Cc: davem, rajur, netdev, linux-kernel, Yang Li
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 <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <abaci-bugfix@linux.alibaba.com>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] cxgb4: remove redundant NULL check
2021-01-26 2:50 [PATCH net-next] cxgb4: remove redundant NULL check Yang Li
@ 2021-01-27 6:34 ` Raju Rangoju
2021-01-27 21:13 ` Jakub Kicinski
0 siblings, 1 reply; 3+ messages in thread
From: Raju Rangoju @ 2021-01-27 6:34 UTC (permalink / raw)
To: Yang Li; +Cc: kuba, davem, netdev, linux-kernel
On Tuesday, January 01/26/21, 2021 at 10:50:13 +0800, Yang Li wrote:
> 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 <abaci@linux.alibaba.com>
> Signed-off-by: Yang Li <abaci-bugfix@linux.alibaba.com>
> ---
> 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)
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().
> - 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);
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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] cxgb4: remove redundant NULL check
2021-01-27 6:34 ` Raju Rangoju
@ 2021-01-27 21:13 ` Jakub Kicinski
0 siblings, 0 replies; 3+ messages in thread
From: Jakub Kicinski @ 2021-01-27 21:13 UTC (permalink / raw)
To: Raju Rangoju; +Cc: Yang Li, davem, netdev, linux-kernel
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:
> > 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 <abaci@linux.alibaba.com>
> > Signed-off-by: Yang Li <abaci-bugfix@linux.alibaba.com>
> > 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.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-01-27 21:14 UTC | newest]
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