Re: [PATCH] usb: ehci-orion: Handle errors of clk_prepare_enable() in probe

[Dan Carpenter]

On Thu, Aug 26, 2021 at 07:26:22PM +0300, Evgeny Novikov wrote:
> I added Dan to the discussion since he is a developer of one of such
> tools.

Thanks for that...  :P

I never warn about "forgot to check the return" bugs except in the case
of error pointers or allocation failures.  There are too many false
positives.  If people want to do that they should add a __must_check
attribute to the function.

You linked to another thread: https://lkml.org/lkml/2021/8/17/239

That patch isn't correct.  Miquel was on the right track but not 100%.
The nand_scan() calls mxic_nfc_clk_enable() so we should disable it
until it has been successfully enabled.  The current code can trigger a
WARN() in __clk_disable().  In other words it should have been:

diff --git a/drivers/mtd/nand/raw/mxic_nand.c b/drivers/mtd/nand/raw/mxic_nand.c
index da1070993994..87aef98f5b9d 100644
--- a/drivers/mtd/nand/raw/mxic_nand.c
+++ b/drivers/mtd/nand/raw/mxic_nand.c
@@ -535,11 +535,11 @@ static int mxic_nfc_probe(struct platform_device *pdev)
 	err = devm_request_irq(&pdev->dev, irq, mxic_nfc_isr,
 			       0, "mxic-nfc", nfc);
 	if (err)
-		goto fail;
+		return err;
 
 	err = nand_scan(nand_chip, 1);
 	if (err)
-		goto fail;
+		return err;
 
 	err = mtd_device_register(mtd, NULL, 0);
 	if (err)

nand_scan() error handling is still leaky, but it's hard to fix without
re-working the API.

Anyway, thanks for the fixes.  I've been inspired by the Linux Driver
Verification project work.

regards,
dan carpenter