From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: dmaengine: rcar-dmac: Check the done lists in rcar_dmac_chan_get_residue() From: Yoshihiro Shimoda Message-Id: <1517565915-14234-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> Date: Fri, 2 Feb 2018 19:05:15 +0900 To: vinod.koul@intel.com Cc: dmaengine@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Yoshihiro Shimoda List-ID: VGhpcyBwYXRjaCBmaXhlcyBhbiBpc3N1ZSB0aGF0IGEgcmFjZSBjb25kaXRpb24gaGFwcGVucyBi ZXR3ZWVuIGEgY2xpZW50CmRyaXZlciBhbmQgdGhlIHJjYXItZG1hYyBkcml2ZXI6CgotIFRoZSBy Y2FyX2RtYWNfaXNyX3RyYW5zZmVyX2VuZCgpIGlzIGNhbGxlZC4KIC0gVGhlIGRvbmUgbGlzdCBh cHBlYXJzLCBhbmQgZGVzYy5ydW5uaW5nIGlzIHRoZSBuZXh0IGFjdGl2ZSBsaXN0LgotIHJjYXJf ZG1hY19jaGFuX2dldF9yZXNpZHVlKCkgaXMgY2FsbGVkIGJ5IGEgY2xpZW50IGRyaXZlciBiZWZv cmUKICByY2FyX2RtYWNfaXNyX2NoYW5uZWxfdGhyZWFkKCkgaXMgY2FsbGVkLgogLSBUaGUgcmNh cl9kbWFjX2NoYW5fZ2V0X3Jlc2lkdWUoKSB3aWxsIG5vdCBmaW5kIGFueSBkZXNjcmlwdG9ycy4K IC0gQW5kLCB0aGUgZm9sbG93aW5nIFdBUk5JTkcgaGFwcGVuczoKCVdBUk4oMSwgIk5vIGRlc2Ny aXB0b3IgZm9yIGNvb2tpZSEiKTsKClRoZSBzaC1zY2kgZHJpdmVyIHdpdGggSFNDSUYgKDkyMSw2 MDBicHMpIG9uIFItQ2FyIEgzIGNhbiBjYXVzZSB0aGlzCnNpdHVhdGlvbi4KU28sIHRoaXMgcGF0 Y2ggY2hlY2tzIHRoZSBkb25lIGxpc3RzIGluIHJjYXJfZG1hY19jaGFuX2dldF9yZXNpZHVlKCkK YW5kIHJldHVybnMgemVybyBpZiB0aGUgZG9uZSBsaXN0cyBoYXMgdGhlIGFyZ3VtZW50IGNvb2tp ZS4KClRlc3RlZC1ieTogTmd1eWVuIFZpZXQgRHVuZyA8ZHVuZy5uZ3V5ZW4uYWpAcmVuZXNhcy5j b20+ClNpZ25lZC1vZmYtYnk6IFlvc2hpaGlybyBTaGltb2RhIDx5b3NoaWhpcm8uc2hpbW9kYS51 aEByZW5lc2FzLmNvbT4KLS0tCiBkcml2ZXJzL2RtYS9zaC9yY2FyLWRtYWMuYyB8IDkgKysrKysr KysrCiAxIGZpbGUgY2hhbmdlZCwgOSBpbnNlcnRpb25zKCspCgpkaWZmIC0tZ2l0IGEvZHJpdmVy cy9kbWEvc2gvcmNhci1kbWFjLmMgYi9kcml2ZXJzL2RtYS9zaC9yY2FyLWRtYWMuYwppbmRleCAy YjJjN2RiLi5mNzQ4YmU2IDEwMDY0NAotLS0gYS9kcml2ZXJzL2RtYS9zaC9yY2FyLWRtYWMuYwor KysgYi9kcml2ZXJzL2RtYS9zaC9yY2FyLWRtYWMuYwpAQCAtMTI2NCw4ICsxMjY0LDE3IEBAIHN0 YXRpYyB1bnNpZ25lZCBpbnQgcmNhcl9kbWFjX2NoYW5fZ2V0X3Jlc2lkdWUoc3RydWN0IHJjYXJf ZG1hY19jaGFuICpjaGFuLAogCSAqIElmIHRoZSBjb29raWUgZG9lc24ndCBjb3JyZXNwb25kIHRv IHRoZSBjdXJyZW50bHkgcnVubmluZyB0cmFuc2ZlcgogCSAqIHRoZW4gdGhlIGRlc2NyaXB0b3Ig aGFzbid0IGJlZW4gcHJvY2Vzc2VkIHlldCwgYW5kIHRoZSByZXNpZHVlIGlzCiAJICogZXF1YWwg dG8gdGhlIGZ1bGwgZGVzY3JpcHRvciBzaXplLgorCSAqIEFsc28sIGEgY2xpZW50IGRyaXZlciBp cyBwb3NzaWJsZSB0byBjYWxsIHRoaXMgZnVuY3Rpb24gYmVmb3JlCisJICogcmNhcl9kbWFjX2lz cl9jaGFubmVsX3RocmVhZCgpIHJ1bnMuIEluIHRoaXMgY2FzZSwgdGhlICJkZXNjLnJ1bm5pbmci CisJICogd2lsbCBiZSB0aGUgbmV4dCBkZXNjcmlwdG9yLCBhbmQgdGhlIGRvbmUgbGlzdCB3aWxs IGFwcGVhci4gU28sIGlmCisJICogdGhlIGFyZ3VtZW50IGNvb2tpZSBtYXRjaGVzIHRoZSBkb25l IGxpc3QncyBjb29raWUsIHdlIGNhbiBhc3N1bWUKKwkgKiB0aGUgcmVzaWR1ZSBpcyB6ZXJvLgog CSAqLwogCWlmIChjb29raWUgIT0gZGVzYy0+YXN5bmNfdHguY29va2llKSB7CisJCWxpc3RfZm9y X2VhY2hfZW50cnkoZGVzYywgJmNoYW4tPmRlc2MuZG9uZSwgbm9kZSkgeworCQkJaWYgKGNvb2tp ZSA9PSBkZXNjLT5hc3luY190eC5jb29raWUpCisJCQkJcmV0dXJuIDA7CisJCX0KIAkJbGlzdF9m b3JfZWFjaF9lbnRyeShkZXNjLCAmY2hhbi0+ZGVzYy5wZW5kaW5nLCBub2RlKSB7CiAJCQlpZiAo Y29va2llID09IGRlc2MtPmFzeW5jX3R4LmNvb2tpZSkKIAkJCQlyZXR1cm4gZGVzYy0+c2l6ZTsK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relmlor3.renesas.com ([210.160.252.173]:64603 "EHLO relmlie2.idc.renesas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750799AbeBBKKB (ORCPT ); Fri, 2 Feb 2018 05:10:01 -0500 From: Yoshihiro Shimoda To: vinod.koul@intel.com Cc: dmaengine@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Yoshihiro Shimoda Subject: [PATCH] dmaengine: rcar-dmac: Check the done lists in rcar_dmac_chan_get_residue() Date: Fri, 2 Feb 2018 19:05:15 +0900 Message-Id: <1517565915-14234-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-renesas-soc-owner@vger.kernel.org List-ID: 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 Signed-off-by: Yoshihiro Shimoda --- drivers/dma/sh/rcar-dmac.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index 2b2c7db..f748be6 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -1264,8 +1264,17 @@ 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; -- 1.9.1