From b6ea03562f04382776ad825624daefe27f5d3f9c Mon Sep 17 00:00:00 2001 From: Bob Copeland Date: Sat, 10 Jan 2009 14:42:54 -0500 Subject: [PATCH] ath5k: fix bf->skb==NULL panic in ath5k_tasklet_rx Under memory pressure, we may not be able to allocate a new skb for new packets. If the allocation fails, ath5k_tasklet_rx will exit but will leave a buffer in the list with a NULL skb, eventually triggering a BUG_ON. Extract the skb allocation from ath5k_rxbuf_setup() and change the tasklet to allocate the next skb before accepting a packet. Changes-licensed-under: 3-Clause-BSD Signed-off-by: Bob Copeland Signed-off-by: John W. Linville --- drivers/net/wireless/ath5k/base.c | 85 +++++++++++++++++++------------ 1 file changed, 53 insertions(+), 32 deletions(-) diff --git a/drivers/net/wireless/ath5k/base.c b/drivers/net/wireless/ath5k/base.c index fdf7733e76e1..d3178731adc6 100644 --- a/drivers/net/wireless/ath5k/base.c +++ b/drivers/net/wireless/ath5k/base.c @@ -1096,6 +1096,42 @@ ath5k_hw_to_driver_rix(struct ath5k_softc *sc, int hw_rix) * Buffers setup * \***************/ +static +struct sk_buff *ath5k_rx_skb_alloc(struct ath5k_softc *sc, dma_addr_t *skb_addr) +{ + struct sk_buff *skb; + unsigned int off; + + /* + * Allocate buffer with headroom_needed space for the + * fake physical layer header at the start. + */ + skb = dev_alloc_skb(sc->rxbufsize + sc->cachelsz - 1); + + if (!skb) { + ATH5K_ERR(sc, "can't alloc skbuff of size %u\n", + sc->rxbufsize + sc->cachelsz - 1); + return NULL; + } + /* + * Cache-line-align. This is important (for the + * 5210 at least) as not doing so causes bogus data + * in rx'd frames. + */ + off = ((unsigned long)skb->data) % sc->cachelsz; + if (off != 0) + skb_reserve(skb, sc->cachelsz - off); + + *skb_addr = pci_map_single(sc->pdev, + skb->data, sc->rxbufsize, PCI_DMA_FROMDEVICE); + if (unlikely(pci_dma_mapping_error(sc->pdev, *skb_addr))) { + ATH5K_ERR(sc, "%s: DMA mapping failed\n", __func__); + dev_kfree_skb(skb); + return NULL; + } + return skb; +} + static int ath5k_rxbuf_setup(struct ath5k_softc *sc, struct ath5k_buf *bf) { @@ -1103,37 +1139,11 @@ ath5k_rxbuf_setup(struct ath5k_softc *sc, struct ath5k_buf *bf) struct sk_buff *skb = bf->skb; struct ath5k_desc *ds; - if (likely(skb == NULL)) { - unsigned int off; - - /* - * Allocate buffer with headroom_needed space for the - * fake physical layer header at the start. - */ - skb = dev_alloc_skb(sc->rxbufsize + sc->cachelsz - 1); - if (unlikely(skb == NULL)) { - ATH5K_ERR(sc, "can't alloc skbuff of size %u\n", - sc->rxbufsize + sc->cachelsz - 1); + if (!skb) { + skb = ath5k_rx_skb_alloc(sc, &bf->skbaddr); + if (!skb) return -ENOMEM; - } - /* - * Cache-line-align. This is important (for the - * 5210 at least) as not doing so causes bogus data - * in rx'd frames. - */ - off = ((unsigned long)skb->data) % sc->cachelsz; - if (off != 0) - skb_reserve(skb, sc->cachelsz - off); - bf->skb = skb; - bf->skbaddr = pci_map_single(sc->pdev, - skb->data, sc->rxbufsize, PCI_DMA_FROMDEVICE); - if (unlikely(pci_dma_mapping_error(sc->pdev, bf->skbaddr))) { - ATH5K_ERR(sc, "%s: DMA mapping failed\n", __func__); - dev_kfree_skb(skb); - bf->skb = NULL; - return -ENOMEM; - } } /* @@ -1662,7 +1672,8 @@ ath5k_tasklet_rx(unsigned long data) { struct ieee80211_rx_status rxs = {}; struct ath5k_rx_status rs = {}; - struct sk_buff *skb; + struct sk_buff *skb, *next_skb; + dma_addr_t next_skb_addr; struct ath5k_softc *sc = (void *)data; struct ath5k_buf *bf, *bf_last; struct ath5k_desc *ds; @@ -1747,10 +1758,17 @@ ath5k_tasklet_rx(unsigned long data) goto next; } accept: + next_skb = ath5k_rx_skb_alloc(sc, &next_skb_addr); + + /* + * If we can't replace bf->skb with a new skb under memory + * pressure, just skip this packet + */ + if (!next_skb) + goto next; + pci_unmap_single(sc->pdev, bf->skbaddr, sc->rxbufsize, PCI_DMA_FROMDEVICE); - bf->skb = NULL; - skb_put(skb, rs.rs_datalen); /* The MAC header is padded to have 32-bit boundary if the @@ -1823,6 +1841,9 @@ accept: ath5k_check_ibss_tsf(sc, skb, &rxs); __ieee80211_rx(sc->hw, skb, &rxs); + + bf->skb = next_skb; + bf->skbaddr = next_skb_addr; next: list_move_tail(&bf->list, &sc->rxbuf); } while (ath5k_rxbuf_setup(sc, bf) == 0); -- 2.20.1