From: Quintin Pitts Date: Fri, 9 Apr 2010 19:37:38 +0000 (+0200) Subject: p54pci: prevent stuck rx-ring on slow system X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5988f385b4cffa9ca72c5be0188e5f4c9ef46d82;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git p54pci: prevent stuck rx-ring on slow system This patch fixes an old problem, which - under certain circumstances - could cause the device to become unresponsive. most of p54pci's rx-ring management is implemented in just two distinct standalone functions. p54p_check_rx_ring takes care of processing incoming data, while p54p_refill_rx_ring tries to replenish all depleted communication buffers. This has always worked fine on my fast machine, but now I know there is a hidden race... The most likely candidate here is ring_control->device_idx. Quintin Pitts had already analyzed the culprit and posted a patch back in Oct 2009. But sadly, no one's picked up on this. ( https://patchwork.kernel.org/patch/53079/ [2 & 3] ). This patch does the same way, except that it also prioritize rx data processing, simply because tx routines *can* wait. Reported-by: Sean Young Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=11386 Reported-by: Quintin Pitts Signed-off-by: Quintin Pitts Signed-off-by: Christian Lamparter Signed-off-by: John W. Linville --- diff --git a/drivers/net/wireless/p54/p54pci.c b/drivers/net/wireless/p54/p54pci.c index ed4bdffdd63e..aa29663bf6c9 100644 --- a/drivers/net/wireless/p54/p54pci.c +++ b/drivers/net/wireless/p54/p54pci.c @@ -131,7 +131,7 @@ static int p54p_upload_firmware(struct ieee80211_hw *dev) static void p54p_refill_rx_ring(struct ieee80211_hw *dev, int ring_index, struct p54p_desc *ring, u32 ring_limit, - struct sk_buff **rx_buf) + struct sk_buff **rx_buf, u32 index) { struct p54p_priv *priv = dev->priv; struct p54p_ring_control *ring_control = priv->ring_control; @@ -139,7 +139,7 @@ static void p54p_refill_rx_ring(struct ieee80211_hw *dev, idx = le32_to_cpu(ring_control->host_idx[ring_index]); limit = idx; - limit -= le32_to_cpu(ring_control->device_idx[ring_index]); + limit -= le32_to_cpu(index); limit = ring_limit - limit; i = idx % ring_limit; @@ -231,7 +231,7 @@ static void p54p_check_rx_ring(struct ieee80211_hw *dev, u32 *index, i %= ring_limit; } - p54p_refill_rx_ring(dev, ring_index, ring, ring_limit, rx_buf); + p54p_refill_rx_ring(dev, ring_index, ring, ring_limit, rx_buf, *index); } static void p54p_check_tx_ring(struct ieee80211_hw *dev, u32 *index, @@ -276,14 +276,6 @@ static void p54p_tasklet(unsigned long dev_id) struct p54p_priv *priv = dev->priv; struct p54p_ring_control *ring_control = priv->ring_control; - p54p_check_tx_ring(dev, &priv->tx_idx_mgmt, 3, ring_control->tx_mgmt, - ARRAY_SIZE(ring_control->tx_mgmt), - priv->tx_buf_mgmt); - - p54p_check_tx_ring(dev, &priv->tx_idx_data, 1, ring_control->tx_data, - ARRAY_SIZE(ring_control->tx_data), - priv->tx_buf_data); - p54p_check_rx_ring(dev, &priv->rx_idx_mgmt, 2, ring_control->rx_mgmt, ARRAY_SIZE(ring_control->rx_mgmt), priv->rx_buf_mgmt); @@ -292,6 +284,14 @@ static void p54p_tasklet(unsigned long dev_id) wmb(); P54P_WRITE(dev_int, cpu_to_le32(ISL38XX_DEV_INT_UPDATE)); + + p54p_check_tx_ring(dev, &priv->tx_idx_mgmt, 3, ring_control->tx_mgmt, + ARRAY_SIZE(ring_control->tx_mgmt), + priv->tx_buf_mgmt); + + p54p_check_tx_ring(dev, &priv->tx_idx_data, 1, ring_control->tx_data, + ARRAY_SIZE(ring_control->tx_data), + priv->tx_buf_data); } static irqreturn_t p54p_interrupt(int irq, void *dev_id) @@ -444,10 +444,10 @@ static int p54p_open(struct ieee80211_hw *dev) priv->rx_idx_mgmt = priv->tx_idx_mgmt = 0; p54p_refill_rx_ring(dev, 0, priv->ring_control->rx_data, - ARRAY_SIZE(priv->ring_control->rx_data), priv->rx_buf_data); + ARRAY_SIZE(priv->ring_control->rx_data), priv->rx_buf_data, 0); p54p_refill_rx_ring(dev, 2, priv->ring_control->rx_mgmt, - ARRAY_SIZE(priv->ring_control->rx_mgmt), priv->rx_buf_mgmt); + ARRAY_SIZE(priv->ring_control->rx_mgmt), priv->rx_buf_mgmt, 0); P54P_WRITE(ring_control_base, cpu_to_le32(priv->ring_control_dma)); P54P_READ(ring_control_base);