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 <swarren@nvidia.com> Signed-off-by: Colin Cross <ccross@android.com>
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@ -127,6 +127,7 @@ struct tegra_dma_channel {
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#define NV_DMA_MAX_CHANNELS 32
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static bool tegra_dma_initialized;
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static DEFINE_MUTEX(tegra_dma_lock);
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static DECLARE_BITMAP(channel_usage, NV_DMA_MAX_CHANNELS);
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@ -352,6 +353,9 @@ struct tegra_dma_channel *tegra_dma_allocate_channel(int mode)
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int channel;
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struct tegra_dma_channel *ch = NULL;
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if (WARN_ON(!tegra_dma_initialized))
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return NULL;
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mutex_lock(&tegra_dma_lock);
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/* first channel is the shared channel */
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@ -678,6 +682,8 @@ int __init tegra_dma_init(void)
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void __iomem *addr;
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struct clk *c;
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bitmap_fill(channel_usage, NV_DMA_MAX_CHANNELS);
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c = clk_get_sys("tegra-dma", NULL);
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if (IS_ERR(c)) {
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pr_err("Unable to get clock for APB DMA\n");
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@ -696,18 +702,9 @@ int __init tegra_dma_init(void)
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writel(0xFFFFFFFFul >> (31 - TEGRA_SYSTEM_DMA_CH_MAX),
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addr + APB_DMA_IRQ_MASK_SET);
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memset(channel_usage, 0, sizeof(channel_usage));
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memset(dma_channels, 0, sizeof(dma_channels));
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/* Reserve all the channels we are not supposed to touch */
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for (i = 0; i < TEGRA_SYSTEM_DMA_CH_MIN; i++)
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__set_bit(i, channel_usage);
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for (i = TEGRA_SYSTEM_DMA_CH_MIN; i <= TEGRA_SYSTEM_DMA_CH_MAX; i++) {
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struct tegra_dma_channel *ch = &dma_channels[i];
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__clear_bit(i, channel_usage);
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ch->id = i;
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snprintf(ch->name, TEGRA_DMA_NAME_SIZE, "dma_channel_%d", i);
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@ -726,14 +723,15 @@ int __init tegra_dma_init(void)
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goto fail;
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}
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ch->irq = irq;
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__clear_bit(i, channel_usage);
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}
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/* mark the shared channel allocated */
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__set_bit(TEGRA_SYSTEM_DMA_CH_MIN, channel_usage);
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for (i = TEGRA_SYSTEM_DMA_CH_MAX+1; i < NV_DMA_MAX_CHANNELS; i++)
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__set_bit(i, channel_usage);
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tegra_dma_initialized = true;
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return ret;
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return 0;
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fail:
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writel(0, addr + APB_DMA_GEN);
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for (i = TEGRA_SYSTEM_DMA_CH_MIN; i <= TEGRA_SYSTEM_DMA_CH_MAX; i++) {
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