From fdb28589b10f1bd4c407ea304399c2ff1cae1504 Mon Sep 17 00:00:00 2001 From: Raja Mani Date: Mon, 21 Nov 2011 12:26:51 +0530 Subject: [PATCH] ath6kl: Use mutex to protect dma buffer in sync read write Firmware crashes while starting Soft AP in 32 bit x86 platform. The reason is that the single dma buffer (ar_sdio->dma_buffer) is used in ath6kl_sdio_read_write_sync() for unaligned buffer handling and this function is called in the multiple context at the same time. So, finally hits dma buffer corruption and firmware crash. Mutex is used to protect dma buffer to avoid data corruption. Spin lock can not used to fix this issue since mmc stack read/write calls may for sleep. Observed this issue with recently commited patch "ath6kl: Claim sdio function only at appropriate places" 861dd058f495973c7ad2a44b8f68f3cc05733eab kvalo: change name of mutex to more descriptive and add a comment about what it protects Signed-off-by: Raja Mani Signed-off-by: Kalle Valo --- drivers/net/wireless/ath/ath6kl/sdio.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/wireless/ath/ath6kl/sdio.c b/drivers/net/wireless/ath/ath6kl/sdio.c index b52b90d..eecf88c 100644 --- a/drivers/net/wireless/ath/ath6kl/sdio.c +++ b/drivers/net/wireless/ath/ath6kl/sdio.c @@ -39,8 +39,12 @@ struct ath6kl_sdio { struct bus_request bus_req[BUS_REQUEST_MAX_NUM]; struct ath6kl *ar; + u8 *dma_buffer; + /* protects access to dma_buffer */ + struct mutex dma_buffer_mutex; + /* scatter request list head */ struct list_head scat_req; @@ -395,6 +399,7 @@ static int ath6kl_sdio_read_write_sync(struct ath6kl *ar, u32 addr, u8 *buf, if (buf_needs_bounce(buf)) { if (!ar_sdio->dma_buffer) return -ENOMEM; + mutex_lock(&ar_sdio->dma_buffer_mutex); tbuf = ar_sdio->dma_buffer; memcpy(tbuf, buf, len); bounced = true; @@ -405,6 +410,9 @@ static int ath6kl_sdio_read_write_sync(struct ath6kl *ar, u32 addr, u8 *buf, if ((request & HIF_READ) && bounced) memcpy(buf, tbuf, len); + if (bounced) + mutex_unlock(&ar_sdio->dma_buffer_mutex); + return ret; } @@ -1219,6 +1227,7 @@ static int ath6kl_sdio_probe(struct sdio_func *func, spin_lock_init(&ar_sdio->lock); spin_lock_init(&ar_sdio->scat_lock); spin_lock_init(&ar_sdio->wr_async_lock); + mutex_init(&ar_sdio->dma_buffer_mutex); INIT_LIST_HEAD(&ar_sdio->scat_req); INIT_LIST_HEAD(&ar_sdio->bus_req_freeq); -- 2.7.4