On 26.09.2023 12:53, Chengfeng Ye wrote: > 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@xxxxxxxxx> Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > --- > 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 f62703cebb77..4b4c129c09e7 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; > } Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
