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>
