On Wed, Sep 14, 2022 at 07:26:36AM +0300, Farber, Eliav wrote: > On 9/13/2022 8:01 PM, Andy Shevchenko wrote: > > On Tue, Sep 13, 2022 at 05:40:16PM +0300, Farber, Eliav wrote: > > > On 9/13/2022 4:06 PM, Farber, Eliav wrote: ... > > > It seems like debugfs_attr_write() calls simple_attr_write() and it uses > > > kstrtoull(), which is why it fails when setting a negative value. > > > This is the same also in v6.0-rc5. > > > > > > debugfs_attr_read() on the other hand does show the correct value also > > > when j is negative. > > > > Which puzzles me since there is a few drivers that use %lld. > > Yeah, changing it to > > > > ret = sscanf(attr->set_buf, attr->fmt, &val); > > if (ret != 1) > > ret = -EINVAL; > > > > probably can fix that. Dunno if debugfs maintainer is okay with this. > > > > P.S. This needs revisiting all format strings to see if there are no > > additional > > characters, otherwise that needs to be addressed first, if feasible. > > I was thinking of making such a correction: > > - ret = kstrtoull(attr->set_buf, 0, &val); > + if (attr->set_buf[0] == '-') > + ret = kstrtoll(attr->set_buf, 0, &val); > + else > + ret = kstrtoull(attr->set_buf, 0, &val); > > and when I tested the change it worked, but then I noticed this commit: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/libfs.c?h=v6.0-rc5&id=488dac0c9237647e9b8f788b6a342595bfa40bda > > According to this, it previously used simple_strtoll() which supports > negative values, but was changed to use kstrtoull() to deliberately > return '-EINVAL' if it gets a negative value. > > So I’m not sure debugfs maintainers will be okay with a fix that > basically reverts the commit I mentioned. > Hence, what do you suggest to do with my commit? > Is it ok to leave it as it is today? Meanwhile asking is not a problem, at least we will know for sure. And yes, leave it as is, but point to the thread where you asking the clarification. -- With Best Regards, Andy Shevchenko
