On Fri, Aug 12, 2022 at 07:46:42AM +0200, Greg KH wrote: > On Fri, Aug 12, 2022 at 10:54:38AM +0800, lihuisong (C) wrote: > > > > 在 2022/8/12 9:48, Dongdong Liu 写道: > > > cc Huisong who found the issue. > > > > > > On 2022/8/10 16:21, Greg KH wrote: > > > > On Wed, Aug 10, 2022 at 08:11:33AM +0200, Greg KH wrote: > > > > > On Wed, Aug 10, 2022 at 08:54:36AM +0300, Krzysztof Kozlowski wrote: > > > > > > On 09/08/2022 22:21, Bjorn Helgaas wrote: > > > > > > > [+cc regressions list] > > > > > > > > > > > > > > 23d99baf9d72 appeared in v5.19-rc1. > > > > > > > > > > > > > > On Tue, Aug 09, 2022 at 11:29:43AM -0700, Stephen Hemminger wrote: > > > > > > > > This commit broke the driver override script in DPDK. > > > > > > > > This is an API/ABI breakage, please revert or fix the commit. > > > > > > > > > > > > > > > > Report of problem: > > > > > > > > http://mails.dpdk.org/archives/dev/2022-August/247794.html > > > > > > > > > > > > Thanks for the report. I'll take a look. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > commit 23d99baf9d729ca30b2fb6798a7b403a37bfb800 > > > > > > > > Author: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> > > > > > > > > Date: Tue Apr 19 13:34:28 2022 +0200 > > > > > > > > > > > > > > > > PCI: Use driver_set_override() instead of open-coding > > > > > > > > > > > > > > > > Use a helper to set driver_override to the > > > > > > > > reduce amount of duplicated > > > > > > > > code. Make the driver_override field const > > > > > > > > char, because it is not > > > > > > > > modified by the core and it matches other subsystems. > > > > > > > > > > > > > > > > Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> > > > > > > > > Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > > > > > > > Signed-off-by: Krzysztof Kozlowski > > > > > > > > <krzysztof.kozlowski@xxxxxxxxxx> > > > > > > > > Link: https://lore.kernel.org/r/20220419113435.246203-6-krzysztof.kozlowski@xxxxxxxxxx > > > > > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > > > > > > > > > > > > > > > > > > > > > The script is sending single nul character to remove override > > > > > > > > and that no longer works. > > > > > > > > > > > > The sysfs API clearly states: > > > > > > "and > > > > > > may be cleared with an empty string (echo > driver_override)." > > > > > > Documentation/ABI/testing/sysfs-bus-pci > > > > > > > > > > > > Sending other data and expecting the same result is not conforming to > > > > > > API. Therefore we have usual example of some undocumented > > > > > > behavior which > > > > > > user-space started relying on and instead using API, user-space expect > > > > > > that undocumented behavior to be back. > > > > > > > > > > > > Yay! I wonder what is the point to even describe the ABI if user-space > > > > > > can simply ignore it? > > > > > > > > > > One can argue that a string of just '\0' is an "empty string" and we > > > > > should be able to properly handle this in the kernel. Heck, > > > > > "\0\0\0\0\0\0" is also an "empty string", right? > > > > > > > > > > I don't have an issue with fixing the kernel up here, it should be able > > > > > to handle this. > > > > > > > > Stephen, does the patch below fix this for you? > > > > > > > > thanks, > > > > > > > > greg k-h > > > > > > > > ----------------- > > > > > > > > diff --git a/drivers/base/driver.c b/drivers/base/driver.c > > > > index 15a75afe6b84..676b6275d5b5 100644 > > > > --- a/drivers/base/driver.c > > > > +++ b/drivers/base/driver.c > > > > @@ -63,6 +63,12 @@ int driver_set_override(struct device *dev, const > > > > char **override, > > > > if (len >= (PAGE_SIZE - 1)) > > > > return -EINVAL; > > > > > > > > + /* > > > > + * Compute the real length of the string in case userspace > > > > sends us a > > > > + * bunch of \0 characters like python likes to do. > > > > + */ > > > > + len = strlen(s); > > > > + > > > > if (!len) { > > > > /* Empty string passed - clear override */ > > > > device_lock(dev); > > > > . > > > > > > > This patch looks good, @huisong, please help to test the patch. > > > > > > Thanks, > > > Dongdong > > > . > > Tested-by: Huisong Li <lihuisong@xxxxxxxxxx> > > Wonderful, thanks! I'll queue this up to send to Linus after -rc1 is > out. Sorry for the delay, now sent to lkml: https://lore.kernel.org/r/20220901163734.3583106-1-gregkh@xxxxxxxxxxxxxxxxxxx
