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Message-ID: <4cabffc1-7ff9-4277-b508-5902f42b47cb@kernel.org> Date: Sat, 18 Nov 2023 12:00:08 +0200 From: Roger Quadros <rogerq@...nel.org> To: Uwe Kleine-König <u.kleine-koenig@...gutronix.de> Cc: Siddharth Vadapalli <s-vadapalli@...com>, Ravi Gunasekaran <r-gunasekaran@...com>, Simon Horman <horms@...nel.org>, Yunsheng Lin <linyunsheng@...wei.com>, Stanislav Fomichev <sdf@...gle.com>, Marek Majtyka <alardam@...il.com>, Rob Herring <robh@...nel.org>, Mugunthan V N <mugunthanvnm@...com>, linux-omap@...r.kernel.org, netdev@...r.kernel.org, kernel@...gutronix.de Subject: Re: [PATCH 2/7] net: ethernet: ti: cpsw: Don't error out in .remove() On 17/11/2023 11:16, Uwe Kleine-König wrote: > Returning early from .remove() with an error code still results in the > driver unbinding the device. So the driver core ignores the returned error > code and the resources that were not freed are never catched up. In > combination with devm this also often results in use-after-free bugs. > > If runtime resume fails, it's still important to free all resources, so > don't return with an error code, but emit an error message and continue > freeing acquired stuff. > > This prepares changing cpsw_remove() to return void. > > Fixes: 8a0b6dc958fd ("drivers: net: cpsw: fix wrong regs access in cpsw_remove") > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de> > --- > drivers/net/ethernet/ti/cpsw.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c > index ca4d4548f85e..db5a2ba8a6d4 100644 > --- a/drivers/net/ethernet/ti/cpsw.c > +++ b/drivers/net/ethernet/ti/cpsw.c > @@ -1727,16 +1727,24 @@ static int cpsw_remove(struct platform_device *pdev) > struct cpsw_common *cpsw = platform_get_drvdata(pdev); > int i, ret; > > - ret = pm_runtime_resume_and_get(&pdev->dev); > + ret = pm_runtime_get_sync(&pdev->dev); > if (ret < 0) > - return ret; > + /* There is no need to do something about that. The important > + * thing is to not exit early, but do all cleanup that doesn't > + * require register access. > + */ > + dev_err(&pdev->dev, "runtime resume failed (%pe)\n", > + ERR_PTR(ret)); > > for (i = 0; i < cpsw->data.slaves; i++) > if (cpsw->slaves[i].ndev) > unregister_netdev(cpsw->slaves[i].ndev); > > - cpts_release(cpsw->cpts); > - cpdma_ctlr_destroy(cpsw->dma); > + if (ret >= 0) { > + cpts_release(cpsw->cpts); cpts_release() only does clk_unprepare(). Why not do that in the error path as well? > + cpdma_ctlr_destroy(cpsw->dma); cpdma_ctrl_destroy() not only stops the DMA controller but also frees up the channel and calls dma_free_coherent? We still want to free up the channel and dma_free_coherent in the error path? > + } > + > cpsw_remove_dt(pdev); > pm_runtime_put_sync(&pdev->dev); > pm_runtime_disable(&pdev->dev); -- cheers, -roger
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