forked from luck/tmp_suning_uos_patched
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>
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@ -1301,8 +1301,17 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan,
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* If the cookie doesn't correspond to the currently running transfer
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* then the descriptor hasn't been processed yet, and the residue is
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* equal to the full descriptor size.
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* Also, a client driver is possible to call this function before
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* rcar_dmac_isr_channel_thread() runs. In this case, the "desc.running"
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* will be the next descriptor, and the done list will appear. So, if
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* the argument cookie matches the done list's cookie, we can assume
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* the residue is zero.
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*/
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if (cookie != desc->async_tx.cookie) {
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list_for_each_entry(desc, &chan->desc.done, node) {
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if (cookie == desc->async_tx.cookie)
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return 0;
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}
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list_for_each_entry(desc, &chan->desc.pending, node) {
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if (cookie == desc->async_tx.cookie)
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return desc->size;
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