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author | Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> | 2018-02-02 13:05:15 +0300 |
---|---|---|
committer | Vinod Koul <vinod.koul@intel.com> | 2018-03-05 14:29:35 +0300 |
commit | 3e081628d510b2ddbe493371d9c574d9275da17e (patch) | |
tree | 0f7ffc16ee672273d8706d232012bcf04ead61a5 /drivers | |
parent | db1de9dd83341382f00ed1872d82b266e9137657 (diff) | |
download | linux-3e081628d510b2ddbe493371d9c574d9275da17e.tar.xz |
dmaengine: rcar-dmac: Check the done lists in rcar_dmac_chan_get_residue()
This patch fixes an issue that a race condition happens between a client
driver and the rcar-dmac driver:
- The rcar_dmac_isr_transfer_end() is called.
- The done list appears, and desc.running is the next active list.
- rcar_dmac_chan_get_residue() is called by a client driver before
rcar_dmac_isr_channel_thread() is called.
- The rcar_dmac_chan_get_residue() will not find any descriptors.
- And, the following WARNING happens:
WARN(1, "No descriptor for cookie!");
The sh-sci driver with HSCIF (921,600bps) on R-Car H3 can cause this
situation.
So, this patch checks the done lists in rcar_dmac_chan_get_residue()
and returns zero if the done lists has the argument cookie.
Tested-by: Nguyen Viet Dung <dung.nguyen.aj@renesas.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/dma/sh/rcar-dmac.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index e3ff162c03fc..c64f792e8e15 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -1301,8 +1301,17 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan, * If the cookie doesn't correspond to the currently running transfer * then the descriptor hasn't been processed yet, and the residue is * equal to the full descriptor size. + * Also, a client driver is possible to call this function before + * rcar_dmac_isr_channel_thread() runs. In this case, the "desc.running" + * will be the next descriptor, and the done list will appear. So, if + * the argument cookie matches the done list's cookie, we can assume + * the residue is zero. */ if (cookie != desc->async_tx.cookie) { + list_for_each_entry(desc, &chan->desc.done, node) { + if (cookie == desc->async_tx.cookie) + return 0; + } list_for_each_entry(desc, &chan->desc.pending, node) { if (cookie == desc->async_tx.cookie) return desc->size; |