[PATCH] net: wireless: b43legacy: Replace GFP_ATOMIC with GFP_KERNEL in dma_tx_fragment

[Jia-Ju Bai]

dma_tx_fragment() is never called in atomic context.

dma_tx_fragment() is only called by b43legacy_dma_tx(), which is
only called by b43legacy_tx_work().
b43legacy_tx_work() is only set a parameter of INIT_WORK() in
b43legacy_wireless_init().

Despite never getting called from atomic context,
dma_tx_fragment() calls alloc_skb() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <***@gmail.com>
---
drivers/net/wireless/broadcom/b43legacy/dma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/broadcom/b43legacy/dma.c b/drivers/net/wireless/broadcom/b43legacy/dma.c
index cfa617d..2f0c64c 100644
--- a/drivers/net/wireless/broadcom/b43legacy/dma.c
+++ b/drivers/net/wireless/broadcom/b43legacy/dma.c
@@ -1064,7 +1064,7 @@ static int dma_tx_fragment(struct b43legacy_dmaring *ring,
meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
/* create a bounce buffer in zone_dma on mapping failure. */
if (b43legacy_dma_mapping_error(ring, meta->dmaaddr, skb->len, 1)) {
- bounce_skb = alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
+ bounce_skb = alloc_skb(skb->len, GFP_KERNEL | GFP_DMA);
if (!bounce_skb) {
ring->current_slot = old_top_slot;
ring->used_slots = old_used_slots;

[Michael Büsch]

On Tue, 10 Apr 2018 21:54:19 +0800

Post by Jia-Ju Bai
dma_tx_fragment() is never called in atomic context.
dma_tx_fragment() is only called by b43legacy_dma_tx(), which is
only called by b43legacy_tx_work().
b43legacy_tx_work() is only set a parameter of INIT_WORK() in
b43legacy_wireless_init().
Despite never getting called from atomic context,
dma_tx_fragment() calls alloc_skb() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.
This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.
---
drivers/net/wireless/broadcom/b43legacy/dma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/broadcom/b43legacy/dma.c b/drivers/net/wireless/broadcom/b43legacy/dma.c
index cfa617d..2f0c64c 100644
--- a/drivers/net/wireless/broadcom/b43legacy/dma.c
+++ b/drivers/net/wireless/broadcom/b43legacy/dma.c
@@ -1064,7 +1064,7 @@ static int dma_tx_fragment(struct b43legacy_dmaring *ring,
meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
/* create a bounce buffer in zone_dma on mapping failure. */
if (b43legacy_dma_mapping_error(ring, meta->dmaaddr, skb->len, 1)) {
- bounce_skb = alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
+ bounce_skb = alloc_skb(skb->len, GFP_KERNEL | GFP_DMA);
if (!bounce_skb) {
ring->current_slot = old_top_slot;
ring->used_slots = old_used_slots;

Ack.
I think the GFP_ATOMIC came from the days where we did DMA operations
under spinlock instead of mutex.

The same thing can be done in b43.

Also
setup_rx_descbuffer(ring, desc, meta, GFP_ATOMIC)
could be GFP_KERNEL in dma_rx().
This function is called from IRQ thread context.

[Kalle Valo]

Post by Jia-Ju Bai
dma_tx_fragment() is never called in atomic context.
dma_tx_fragment() is only called by b43legacy_dma_tx(), which is
only called by b43legacy_tx_work().
b43legacy_tx_work() is only set a parameter of INIT_WORK() in
b43legacy_wireless_init().
Despite never getting called from atomic context,
dma_tx_fragment() calls alloc_skb() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.
This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Patch applied to wireless-drivers-next.git, thanks.

6e1d8d1470b2 net: wireless: b43legacy: Replace GFP_ATOMIC with GFP_KERNEL in dma_tx_fragment