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dmaengine: milbeaut-xdmac: Convert to platform remove callback returning void 

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

There is an error path that has the above mentioned problem. This patch
only adds a more drastic error message. To properly fix it,
dmaengine_terminate_sync() must be known to have succeeded (or that it's
safe to not call it as other drivers seem to assume).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231105093415.3704633-8-u.kleine-koenig@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Uwe Kleine-König 2023-11-05 10:34:18 +01:00 committed by Vinod Koul
parent 0fdd1c4ea9
commit 47ee210011
1 changed files with 11 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
drivers/dma/milbeaut-xdmac.c
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@ -368,7 +368,7 @@ disable_xdmac:
return ret;
}
static int milbeaut_xdmac_remove(struct platform_device *pdev)
static void milbeaut_xdmac_remove(struct platform_device *pdev)
{
struct milbeaut_xdmac_device *mdev = platform_get_drvdata(pdev);
struct dma_chan *chan;
@ -383,8 +383,15 @@ static int milbeaut_xdmac_remove(struct platform_device *pdev)
*/
list_for_each_entry(chan, &mdev->ddev.channels, device_node) {
ret = dmaengine_terminate_sync(chan);
if (ret)
return ret;
if (ret) {
/*
* This results in resource leakage and maybe also
* use-after-free errors as e.g. *mdev is kfreed.
*/
dev_alert(&pdev->dev, "Failed to terminate channel %d (%pe)\n",
chan->chan_id, ERR_PTR(ret));
return;
}
milbeaut_xdmac_free_chan_resources(chan);
}
@ -392,8 +399,6 @@ static int milbeaut_xdmac_remove(struct platform_device *pdev)
dma_async_device_unregister(&mdev->ddev);
disable_xdmac(mdev);
return 0;
}
static const struct of_device_id milbeaut_xdmac_match[] = {
@ -404,7 +409,7 @@ MODULE_DEVICE_TABLE(of, milbeaut_xdmac_match);
static struct platform_driver milbeaut_xdmac_driver = {
.probe = milbeaut_xdmac_probe,
.remove = milbeaut_xdmac_remove,
.remove_new = milbeaut_xdmac_remove,
.driver = {
.name = "milbeaut-m10v-xdmac",
.of_match_table = milbeaut_xdmac_match,