[PATCH net-next] sfc: The RX page_ring is optional

[PATCH net-next] sfc: The RX page_ring is optional

[Martin Habets]

The RX page_ring is an optional feature that improves
performance. When allocation fails the driver can still
function, but possibly with a lower bandwidth.
Guard against dereferencing a NULL page_ring.

Fixes: 2768935a4660 ("sfc: reuse pages to avoid DMA mapping/unmapping costs")
Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Reported-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
 drivers/net/ethernet/sfc/falcon/rx.c |    5 +++++
 drivers/net/ethernet/sfc/rx_common.c |    5 +++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/net/ethernet/sfc/falcon/rx.c b/drivers/net/ethernet/sfc/falcon/rx.c
index 11a6aee852e9..57874adfb1b2 100644
--- a/drivers/net/ethernet/sfc/falcon/rx.c
+++ b/drivers/net/ethernet/sfc/falcon/rx.c
@@ -110,6 +110,8 @@ static struct page *ef4_reuse_page(struct ef4_rx_queue *rx_queue)
 	struct ef4_rx_page_state *state;
 	unsigned index;
 
+	if (unlikely(!rx_queue->page_ring))
+		return NULL;
 	index = rx_queue->page_remove & rx_queue->page_ptr_mask;
 	page = rx_queue->page_ring[index];
 	if (page == NULL)
@@ -293,6 +295,9 @@ static void ef4_recycle_rx_pages(struct ef4_channel *channel,
 {
 	struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);
 
+	if (unlikely(!rx_queue->page_ring))
+		return NULL;
+
 	do {
 		ef4_recycle_rx_page(channel, rx_buf);
 		rx_buf = ef4_rx_buf_next(rx_queue, rx_buf);
diff --git a/drivers/net/ethernet/sfc/rx_common.c b/drivers/net/ethernet/sfc/rx_common.c
index 0983abc0cc5f..9ea50617dd04 100644
--- a/drivers/net/ethernet/sfc/rx_common.c
+++ b/drivers/net/ethernet/sfc/rx_common.c
@@ -45,6 +45,8 @@ static struct page *efx_reuse_page(struct efx_rx_queue *rx_queue)
 	unsigned int index;
 	struct page *page;
 
+	if (unlikely(!rx_queue->page_ring))
+		return NULL;
 	index = rx_queue->page_remove & rx_queue->page_ptr_mask;
 	page = rx_queue->page_ring[index];
 	if (page == NULL)
@@ -114,6 +116,9 @@ void efx_recycle_rx_pages(struct efx_channel *channel,
 {
 	struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);
 
+	if (unlikely(!rx_queue->page_ring))
+		return NULL;
+
 	do {
 		efx_recycle_rx_page(channel, rx_buf);
 		rx_buf = efx_rx_buf_next(rx_queue, rx_buf);

Re: [PATCH net-next] sfc: The RX page_ring is optional

[kernel test robot]

Hi Martin,

I love your patch! Yet something to improve:

[auto build test ERROR on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Martin-Habets/sfc-The-RX-page_ring-is-optional/20220101-194123
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git e63a02348958cd7cc8c8401c94de57ad97b5d06c
config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20220102/202201021335.SbR7I6ht-lkp@intel.com/config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project c054402170cd8466683a20385befc0523aba3359)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/162a8e2305bbbba8cd81966114ecce08790c431d
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Martin-Habets/sfc-The-RX-page_ring-is-optional/20220101-194123
        git checkout 162a8e2305bbbba8cd81966114ecce08790c431d
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> drivers/net/ethernet/sfc/rx_common.c:120:3: error: void function 'efx_recycle_rx_pages' should not return a value [-Wreturn-type]
                   return NULL;
                   ^      ~~~~
   1 error generated.
--
>> drivers/net/ethernet/sfc/falcon/rx.c:299:3: error: void function 'ef4_recycle_rx_pages' should not return a value [-Wreturn-type]
                   return NULL;
                   ^      ~~~~
   1 error generated.


vim +/efx_recycle_rx_pages +120 drivers/net/ethernet/sfc/rx_common.c

   111	
   112	/* Recycle the pages that are used by buffers that have just been received. */
   113	void efx_recycle_rx_pages(struct efx_channel *channel,
   114				  struct efx_rx_buffer *rx_buf,
   115				  unsigned int n_frags)
   116	{
   117		struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);
   118	
   119		if (unlikely(!rx_queue->page_ring))
 > 120			return NULL;
   121	
   122		do {
   123			efx_recycle_rx_page(channel, rx_buf);
   124			rx_buf = efx_rx_buf_next(rx_queue, rx_buf);
   125		} while (--n_frags);
   126	}
   127	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org