On Wed, Sep 14, 2022 at 12:32:47PM +0300, Andy Shevchenko wrote: > 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. For the record: $ git grep -n -A1 -w DEFINE_DEBUGFS_ATTRIBUTE | grep ');' | sed 's,.*\(".*%.*"\).*,\1,' | sort | uniq -c 1 "%08llx\n" 5 "0x%016llx\n" 5 "0x%02llx\n" 5 "0x%04llx\n" 13 "0x%08llx\n" 1 "0x%4.4llx\n" 3 "0x%.4llx\n" 4 "0x%llx\n" 1 "%1lld\n" 40 "%lld\n" 2 "%lli\n" 129 "%llu\n" 1 "%#llx\n" 2 "%llx\n" means that sscanf() should work and fix the issue. You may even propose a patch as a starter for a discussion. -- With Best Regards, Andy Shevchenko
