6.6-stable review patch. If anyone has any objections, please let me know.
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From: Chengfeng Ye dg573847474@gmail.com
[ Upstream commit 04d19e65137e3cd4a5004e624c85c762933d115c ]
As &dev->condlock is acquired under irq context along the following call chain from s5p_mfc_irq(), other acquisition of the same lock inside process context or softirq context should disable irq avoid double lock. enc_post_frame_start() seems to be one such function that execute under process context or softirq context.
<deadlock #1>
enc_post_frame_start() --> clear_work_bit() --> spin_loc(&dev->condlock) <interrupt> --> s5p_mfc_irq() --> s5p_mfc_handle_frame() --> clear_work_bit() --> spin_lock(&dev->condlock)
This flaw was found by an experimental static analysis tool I am developing for irq-related deadlock.
To prevent the potential deadlock, the patch change clear_work_bit() inside enc_post_frame_start() to clear_work_bit_irqsave().
Signed-off-by: Chengfeng Ye dg573847474@gmail.com Acked-by: Marek Szyprowski m.szyprowski@samsung.com Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/media/platform/samsung/s5p-mfc/s5p_mfc_enc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/media/platform/samsung/s5p-mfc/s5p_mfc_enc.c b/drivers/media/platform/samsung/s5p-mfc/s5p_mfc_enc.c index f62703cebb77c..4b4c129c09e70 100644 --- a/drivers/media/platform/samsung/s5p-mfc/s5p_mfc_enc.c +++ b/drivers/media/platform/samsung/s5p-mfc/s5p_mfc_enc.c @@ -1297,7 +1297,7 @@ static int enc_post_frame_start(struct s5p_mfc_ctx *ctx) if (ctx->state == MFCINST_FINISHING && ctx->ref_queue_cnt == 0) src_ready = false; if (!src_ready || ctx->dst_queue_cnt == 0) - clear_work_bit(ctx); + clear_work_bit_irqsave(ctx);
return 0; }