From ccac05152e7c6a8103b9e7a801bc995180a800fc Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Wed, 23 Feb 2011 14:49:30 -0700 Subject: [PATCH] ARM: Tegra: DMA: Fail safe if initialization fails tegra_dma_init currently simply bails out early if any initialization fails. This skips various data-structure initialization. In turn, this means that tegra_dma_allocate_channel can still hand out channels. In this case, when tegra_dma_free_channel is called, which calls tegra_dma_cancel, the walking on ch->list will OOPS since the list's next/prev pointers may still be NULL. To solve this, add an explicit "initialized" flag, only set this once _init has fully completed successfully, and have _allocate_channel refuse to hand out channels if this is not set. While at it, simplify _init: * Remove redundant memsets * Use bitmap_fill to mark all channels as in-use up-front, and remove some now-redundant bitmap initialization loops. * Only mark a channel as free once all channel-related initialization has completed. Finally, the successful exit path from _init always has ret==0, so just hard-code that return. The error path still returns ret. Signed-off-by: Stephen Warren Signed-off-by: Colin Cross --- arch/arm/mach-tegra/dma.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/arch/arm/mach-tegra/dma.c b/arch/arm/mach-tegra/dma.c index bd4f62a613aa..e945ae28ee77 100644 --- a/arch/arm/mach-tegra/dma.c +++ b/arch/arm/mach-tegra/dma.c @@ -127,6 +127,7 @@ struct tegra_dma_channel { #define NV_DMA_MAX_CHANNELS 32 +static bool tegra_dma_initialized; static DEFINE_MUTEX(tegra_dma_lock); static DECLARE_BITMAP(channel_usage, NV_DMA_MAX_CHANNELS); @@ -352,6 +353,9 @@ struct tegra_dma_channel *tegra_dma_allocate_channel(int mode) int channel; struct tegra_dma_channel *ch = NULL; + if (WARN_ON(!tegra_dma_initialized)) + return NULL; + mutex_lock(&tegra_dma_lock); /* first channel is the shared channel */ @@ -678,6 +682,8 @@ int __init tegra_dma_init(void) void __iomem *addr; struct clk *c; + bitmap_fill(channel_usage, NV_DMA_MAX_CHANNELS); + c = clk_get_sys("tegra-dma", NULL); if (IS_ERR(c)) { pr_err("Unable to get clock for APB DMA\n"); @@ -696,18 +702,9 @@ int __init tegra_dma_init(void) writel(0xFFFFFFFFul >> (31 - TEGRA_SYSTEM_DMA_CH_MAX), addr + APB_DMA_IRQ_MASK_SET); - memset(channel_usage, 0, sizeof(channel_usage)); - memset(dma_channels, 0, sizeof(dma_channels)); - - /* Reserve all the channels we are not supposed to touch */ - for (i = 0; i < TEGRA_SYSTEM_DMA_CH_MIN; i++) - __set_bit(i, channel_usage); - for (i = TEGRA_SYSTEM_DMA_CH_MIN; i <= TEGRA_SYSTEM_DMA_CH_MAX; i++) { struct tegra_dma_channel *ch = &dma_channels[i]; - __clear_bit(i, channel_usage); - ch->id = i; snprintf(ch->name, TEGRA_DMA_NAME_SIZE, "dma_channel_%d", i); @@ -726,14 +723,15 @@ int __init tegra_dma_init(void) goto fail; } ch->irq = irq; + + __clear_bit(i, channel_usage); } /* mark the shared channel allocated */ __set_bit(TEGRA_SYSTEM_DMA_CH_MIN, channel_usage); - for (i = TEGRA_SYSTEM_DMA_CH_MAX+1; i < NV_DMA_MAX_CHANNELS; i++) - __set_bit(i, channel_usage); + tegra_dma_initialized = true; - return ret; + return 0; fail: writel(0, addr + APB_DMA_GEN); for (i = TEGRA_SYSTEM_DMA_CH_MIN; i <= TEGRA_SYSTEM_DMA_CH_MAX; i++) { -- 2.11.0