| Message ID | 1418038100-4316-1-git-send-email-addy.ke@rock-chips.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Mon, Dec 08, 2014 at 07:28:20PM +0800, Addy Ke wrote: > This bug will cause NULL pointer after commit dfac17, and cause > wrong package in I2S DMA transfer before commit dfac17. > Applied, thanks
diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index 025b905..0773832 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c @@ -1044,6 +1044,10 @@ static bool _trigger(struct pl330_thread *thrd) if (!req) return true; + /* Return if req is running */ + if (idx == thrd->req_running) + return true; + desc = req->desc; ns = desc->rqcfg.nonsecure ? 1 : 0; @@ -1583,6 +1587,8 @@ static int pl330_update(struct pl330_dmac *pl330) descdone = thrd->req[active].desc; thrd->req[active].desc = NULL; + thrd->req_running = -1; + /* Get going again ASAP */ _start(thrd);
This bug will cause NULL pointer after commit dfac17, and cause wrong package in I2S DMA transfer before commit dfac17. Tested on RK3288-pinky2 board. Detail: I2S DMA transfer(sound/core/pcm_dmaengine.c): dmaengine_pcm_prepare_and_submit --> dmaengine_prep_dma_cyclic --> pl330_prep_dma_cyclic --> the case: 1. pl330_submit_req(desc0): thrd->req[0].desc = desc0, thrd->lstenq = 0 2. pl330_submit_req(desc1): thrd->req[1].desc = desc1, thrd->lstenq = 1 3. _start(desc0) by submit_req: thrd->req_running = 0 because: idx = 1 - thrd->lstenq = 0 4. pl330_update(desc0 OK): thrd->req[0].desc = NULL, desc0 to req_done list because: idx = active = thrd->req_running = 0 5. _start(desc1) by pl330_update: thrd->req_running = 1 because: idx = 1 - thrd->lstenq = 0, but thrd->req[0].desc == NULL, so: idx = thrd->lstenq = 1 6. pl330_submit_req(desc2): thrd->req[0].desc = desc2, thrd->lstenq = 0 7. _start(desc1) by submit_req: thrd->req_running = 1 because: idx = 1 - thrd->lstenq = 1 Note: _start started the same descs _start should start desc2 here, NOT desc1 8. pl330_update(desc1 OK): thrd->req[1].desc = NULL, desc1 to req_done list because: idx = active = thrd->req_running = 1 9. _start(desc2) by pl330_update : thrd->req_running = 0 because: idx = 1 - thrd->lstenq = 0 10.pl330_update(desc1 OK, NOT desc2): thrd->req[0].desc = NULL, desc2 to req_done list because: idx = active = thrd->req_running = 0 11.pl330_submit_req(desc3): thrd->req[0].desc = desc3, thrd->lstenq = 0 12.pl330_submit_req(desc4): thrd->req[1].desc = desc4, thrd->lstenq = 1 13._start(desc3) by submit_req: thrd->req_running = 0 because: idx = 1 - thrd->lstenq = 0 14.pl330_update(desc2 OK NOT desc3): thrd->req[0].desc = NULL desc3 to req_done list because: idx = active = thrd->req_running = 0 15._start(desc4) by pl330_update: thrd->req_running = 1 because: idx = 1 - thrd->lstenq = 0, but thrd->req[0].desc == NULL, so: idx = thrd->lstenq = 1 16.pl330_submit_req(desc5): thrd->req[0].desc = desc5, thrd->lstenq = 0 17._start(desc4) by submit_req: thrd->req_running = 1 because: idx = 1 - thrd->lstenq = 1 18.pl330_update(desc3 OK NOT desc4): thrd->req[1].desc = NULL desc4 to req_done list because: idx = active = thrd->req_running = 1 19._start(desc4) by pl330_update: thrd->req_running = 0 because: idx = 1 - thrd->lstenq = 1, but thrd->req[1].desc == NULL, so: idx = thrd->lstenq = 0 20.pl330_update(desc4 OK): thrd->req[0].desc = NULL, desc5 to req_done list because: idx = active = thrd->req_running = 0 21.pl330_update(desc4 OK): 1) before commit dfac17(set req_running -1 in pl330_update/mark_free()): because: active = -1, abort result: desc0-desc5's callback are all called, but step 10 and step 18 go wrong. 2) before commit dfac17: idx = active = thrd->req_runnig = 0 --> descdone = thrd->req[0] = NULL --> list_add_tail(&descdone->rqd, &pl330->req_done); --> got NULL pointer!!! Signed-off-by: Addy Ke <addy.ke@rock-chips.com> --- drivers/dma/pl330.c | 6 ++++++ 1 file changed, 6 insertions(+)