On 07/31/2017 07:56 PM, Thierry Reding wrote:
of_irq_get() may return 0 as well as negative error number on failure, while the driver only checks for the negative values. The driver would then call request_irq(0, ...) in tegra_adma_alloc_chan_resources() and never get valid channel interrupt. Check for 'tdc->irq <= 0' instead and return -ENXIO from the driver's probe iff of_irq_get() returned 0. Fixes: f46b195799b5 ("dmaengine: tegra-adma: Add support for Tegra210 ADMA") Signed-off-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>[...]Index: slave-dma/drivers/dma/tegra210-adma.c =================================================================== --- slave-dma.orig/drivers/dma/tegra210-adma.c +++ slave-dma/drivers/dma/tegra210-adma.c @@ -717,8 +717,8 @@ static int tegra_adma_probe(struct platf tdc->chan_addr = tdma->base_addr + ADMA_CH_REG_OFFSET(i); tdc->irq = of_irq_get(pdev->dev.of_node, i); - if (tdc->irq < 0) { - ret = tdc->irq; + if (tdc->irq <= 0) { + ret = tdc->irq ?: -ENXIO; goto irq_dispose; }I think in this particular case it would be better to just call platform_get_irq(), which already implements the equivalent.
Not that platform_get_irq() was no better (if not worse indeed, as it
s/Not/Note/.
could return 0 both on failure ad success), until I fixed it back in 2016:
s/ad/and/.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e330b9a6bb35dc7097a4f02cb1ae7b6f96df92afOK, I'll try looking into that...I've looked at the commit history and no, I don't agree to use platform_get_irq(): my platform_get_irq() fix landed in mainline later than this driver, so fixing this bug in stable kernels would ensue an extra dependency...Well, surely the platform_get_irq() function should also be fixed in stable kernels, so that all callers can be fixed at the same time.
It has been fixed in 3.16.y, 4.4.y and 4.8.y so far. I haven't received other stable mails yet.
That said, this does fix a bug, and it fixes it in the least invasive way, and the damage I'm complaining about is preexisting, so: Acked-by: Thierry Reding <treding@xxxxxxxxxx>
Thank you! MBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
