From: sashiko-bot@kernel.org
To: "Koichiro Den" <den@valinux.co.jp>
Cc: vkoul@kernel.org, Frank.Li@kernel.org, dmaengine@vger.kernel.org
Subject: Re: [PATCH v2 04/19] dmaengine: dw-edma: Make DMA link list work as a circular buffer
Date: Thu, 23 Jul 2026 09:07:05 +0000 [thread overview]
Message-ID: <20260723090705.9E41D1F000E9@smtp.kernel.org> (raw)
In-Reply-To: <20260723084150.521366-5-den@valinux.co.jp>
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Ring buffer capacity is permanently leaked on error and termination paths because `ll_end` is not advanced.
--
--- Patch [4]: [PATCH v2 04/19] dmaengine: dw-edma: Make DMA link list work as a circular buffer ---
commit 2d5b6554b58830487f70a13eab5e1ac3de304658
Author: Frank Li <Frank.Li@nxp.com>
dmaengine: dw-edma: Make DMA link list work as a circular buffer
This commit updates the driver to use the DMA linked list as a circular
ring buffer. It appends entries at ll_head with the current cycle bit and
reserves the final entry to link back to the start.
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
[ ... ]
> @@ -645,6 +687,8 @@ static void dw_edma_done_interrupt(struct dw_edma_chan *chan)
> DMA_TRANS_NOERROR);
> list_del(&vd->node);
> vchan_cookie_complete(vd);
> + if (!chan->non_ll)
> + chan->ll_end = chan->ll_head;
> }
>
> if (chan->request == EDMA_REQ_PAUSE) {
[Severity: High]
Does this leak ring capacity when descriptors are aborted or terminated?
This block successfully reclaims ring capacity on successful completion by
advancing chan->ll_end. However, if a client driver queues transfers and
then aborts them (for example, via dmaengine_terminate_all() or during an
abort interrupt), the descriptors are removed from the list but chan->ll_end
does not appear to be updated to reflect the aborted descriptors.
Since chan->ll_valid remains true after a termination, subsequent transfers
will bypass the dw_edma_core_reset_ll() ring reset logic and continue
appending to the un-reclaimed ring.
Will this eventually cause dw_edma_core_get_free_num() to permanently return
0 and deadlock the channel once the un-reclaimed slots exhaust the ring?
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260723084150.521366-1-den@valinux.co.jp?part=4
next prev parent reply other threads:[~2026-07-23 9:07 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-23 8:41 [PATCH v2 00/19] dmaengine: dw-edma: Support dynamic LL appends Koichiro Den
2026-07-23 8:41 ` [PATCH v2 01/19] dmaengine: dw-edma: Add dw_edma_core_ll_cur_idx() to get current LL entry index Koichiro Den
2026-07-23 8:41 ` [PATCH v2 02/19] dmaengine: dw-edma: Add dw_edma_core_ll_clear() to clear LL control-word Koichiro Den
2026-07-23 8:41 ` [PATCH v2 03/19] dmaengine: dw-edma: Factor out linked-list transfer start Koichiro Den
2026-07-23 8:41 ` [PATCH v2 04/19] dmaengine: dw-edma: Make DMA link list work as a circular buffer Koichiro Den
2026-07-23 9:07 ` sashiko-bot [this message]
2026-07-23 8:41 ` [PATCH v2 05/19] dmaengine: dw-edma: Add LL interrupt placement policy Koichiro Den
2026-07-23 8:41 ` [PATCH v2 06/19] dmaengine: dw-edma: Move callback result helper before LL helpers Koichiro Den
2026-07-23 8:41 ` [PATCH v2 07/19] dmaengine: dw-edma: Dispatch DONE interrupts by channel request Koichiro Den
2026-07-23 8:55 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 08/19] dmaengine: dw-edma: Centralize LL doorbell decisions Koichiro Den
2026-07-23 9:09 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 09/19] dmaengine: dw-edma: Reclaim issued descriptors from IRQ-paired LL progress Koichiro Den
2026-07-23 9:01 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 10/19] dmaengine: dw-edma: Use HDMA watermarks as progress events Koichiro Den
2026-07-23 8:41 ` [PATCH v2 11/19] dmaengine: dw-edma: Reconcile lost completions from a stopped LLP re-sample Koichiro Den
2026-07-23 8:41 ` [PATCH v2 12/19] dmaengine: dw-edma: Recover stopped channels from tx_status() Koichiro Den
2026-07-23 8:59 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 13/19] dmaengine: dw-edma: Make the LL ring reset a full channel resync Koichiro Den
2026-07-23 9:10 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 14/19] dmaengine: dw-edma: Reset LL state after terminate and abort Koichiro Den
2026-07-23 9:14 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 15/19] dmaengine: dw-edma: Add engine reset and enable operations Koichiro Den
2026-07-23 9:11 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 16/19] dmaengine: dw-edma: Add engine recovery infrastructure Koichiro Den
2026-07-23 9:14 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 17/19] dmaengine: dw-edma: Detect and recover a stalled eDMA engine Koichiro Den
2026-07-23 9:12 ` sashiko-bot
2026-07-23 8:41 ` [PATCH v2 18/19] dmaengine: dw-edma: Dynamically append requests while running Koichiro Den
2026-07-23 8:41 ` [PATCH v2 19/19] dmaengine: dw-edma: Add trace support Koichiro Den
2026-07-23 9:11 ` sashiko-bot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260723090705.9E41D1F000E9@smtp.kernel.org \
--to=sashiko-bot@kernel.org \
--cc=Frank.Li@kernel.org \
--cc=den@valinux.co.jp \
--cc=dmaengine@vger.kernel.org \
--cc=sashiko-reviews@lists.linux.dev \
--cc=vkoul@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox