From ead0e402e50d1101939e4af67891d5b2fa9678b3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= Date: Sun, 5 Nov 2023 10:34:20 +0100 Subject: [PATCH] dmaengine: uniphier-xdmac: Convert to platform remove callback returning void MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Link: https://lore.kernel.org/r/20231105093415.3704633-10-u.kleine-koenig@pengutronix.de Signed-off-by: Vinod Koul --- drivers/dma/uniphier-xdmac.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/drivers/dma/uniphier-xdmac.c b/drivers/dma/uniphier-xdmac.c index 3a8ee2b173b5..3ce2dc2ad9de 100644 --- a/drivers/dma/uniphier-xdmac.c +++ b/drivers/dma/uniphier-xdmac.c @@ -563,7 +563,7 @@ out_unregister_dmac: return ret; } -static int uniphier_xdmac_remove(struct platform_device *pdev) +static void uniphier_xdmac_remove(struct platform_device *pdev) { struct uniphier_xdmac_device *xdev = platform_get_drvdata(pdev); struct dma_device *ddev = &xdev->ddev; @@ -579,15 +579,20 @@ static int uniphier_xdmac_remove(struct platform_device *pdev) */ list_for_each_entry(chan, &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. *xdev is kfreed. + */ + dev_alert(&pdev->dev, "Failed to terminate channel %d (%pe)\n", + chan->chan_id, ERR_PTR(ret)); + return; + } uniphier_xdmac_free_chan_resources(chan); } of_dma_controller_free(pdev->dev.of_node); dma_async_device_unregister(ddev); - - return 0; } static const struct of_device_id uniphier_xdmac_match[] = { @@ -598,7 +603,7 @@ MODULE_DEVICE_TABLE(of, uniphier_xdmac_match); static struct platform_driver uniphier_xdmac_driver = { .probe = uniphier_xdmac_probe, - .remove = uniphier_xdmac_remove, + .remove_new = uniphier_xdmac_remove, .driver = { .name = "uniphier-xdmac", .of_match_table = uniphier_xdmac_match,