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Date: Thu, 14 Mar 2019 14:01:18 +0200
From: Amir Goldstein <amir73il@...il.com>
To: Jan Kara <jack@...e.cz>
Cc: kbuild-all@...org, linux-kernel <linux-kernel@...r.kernel.org>,
linux-mips@...r.kernel.org, Ralf Baechle <ralf@...ux-mips.org>,
Paul Burton <paul.burton@...s.com>,
James Hogan <jhogan@...nel.org>
Subject: Re: fs/notify/fanotify/fanotify.c:198:2: note: in expansion of macro 'pr_warn_ratelimited'
On Thu, Mar 14, 2019 at 10:37 AM Jan Kara <jack@...e.cz> wrote:
>
> AFAICS this is the known problem with weird mips definitions of
> __kernel_fsid_t which uses long whereas all other architectures use int,
> right? Seeing that mips can actually have 8-byte longs, I guess this
> bogosity is just wired in the kernel API and we cannot easily fix it in
> mips (mips guys, correct me if I'm wrong). So what if we just
> unconditionally typed printed values to unsigned int to silence the
> warning?
I don't understand why. To me that sounds like papering over a bug.
See this reply from mips developer Paul Burton:
https://marc.info/?l=linux-fsdevel&m=154783680019904&w=2
mips developers have not replied to the question why __kernel_fsid_t
should use long.
My concern is that we expose __kernel_fsid_t type in uapi header
in struct fanotify_event_info_fid. We should make sure this type
is consistent with glibc's fsid_t.
For reference, the statfs(2) man page says that on Linux
"...fsid_t is defined as struct { int val[2]; }".
Besides, it looks like __kernel_fsid_t got let behind on the
mips posix_types cleanup:
bb8ac181a5cf bury __kernel_nlink_t, make internal nlink_t consistent
86fcd10e9a57 mips: Use generic posix_types.h
To me this seems like an issue that mips developers should
advise on the solution.
Thanks,
Amir.
>
> Honza
>
> On Thu 14-03-19 02:31:52, kbuild test robot wrote:
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head: 5453a3df2a5eb49bc24615d4cf0d66b2aae05e5f
> > commit: e9e0c8903009477b630e37a8b6364b26a00720da fanotify: encode file identifier for FAN_REPORT_FID
> > date: 5 weeks ago
> > config: mips-allmodconfig (attached as .config)
> > compiler: mips-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
> > reproduce:
> > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> > chmod +x ~/bin/make.cross
> > git checkout e9e0c8903009477b630e37a8b6364b26a00720da
> > # save the attached .config to linux build tree
> > GCC_VERSION=7.2.0 make.cross ARCH=mips
> >
> > All warnings (new ones prefixed by >>):
> >
> > In file included from include/linux/kernel.h:14:0,
> > from include/linux/list.h:9,
> > from include/linux/preempt.h:11,
> > from include/linux/spinlock.h:51,
> > from include/linux/fdtable.h:11,
> > from fs/notify/fanotify/fanotify.c:3:
> > fs/notify/fanotify/fanotify.c: In function 'fanotify_encode_fid':
> > include/linux/kern_levels.h:5:18: warning: format '%x' expects argument of type 'unsigned int', but argument 2 has type 'long int' [-Wformat=]
> > #define KERN_SOH "\001" /* ASCII Start Of Header */
> > ^
> > include/linux/printk.h:424:10: note: in definition of macro 'printk_ratelimited'
> > printk(fmt, ##__VA_ARGS__); \
> > ^~~
> > include/linux/kern_levels.h:12:22: note: in expansion of macro 'KERN_SOH'
> > #define KERN_WARNING KERN_SOH "4" /* warning conditions */
> > ^~~~~~~~
> > include/linux/printk.h:440:21: note: in expansion of macro 'KERN_WARNING'
> > printk_ratelimited(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
> > ^~~~~~~~~~~~
> > >> fs/notify/fanotify/fanotify.c:198:2: note: in expansion of macro 'pr_warn_ratelimited'
> > pr_warn_ratelimited("fanotify: failed to encode fid (fsid=%x.%x, "
> > ^~~~~~~~~~~~~~~~~~~
> > fs/notify/fanotify/fanotify.c:198:61: note: format string is defined here
> > pr_warn_ratelimited("fanotify: failed to encode fid (fsid=%x.%x, "
> > ~^
> > %lx
> > In file included from include/linux/kernel.h:14:0,
> > from include/linux/list.h:9,
> > from include/linux/preempt.h:11,
> > from include/linux/spinlock.h:51,
> > from include/linux/fdtable.h:11,
> > from fs/notify/fanotify/fanotify.c:3:
> > include/linux/kern_levels.h:5:18: warning: format '%x' expects argument of type 'unsigned int', but argument 3 has type 'long int' [-Wformat=]
> > #define KERN_SOH "\001" /* ASCII Start Of Header */
> > ^
> > include/linux/printk.h:424:10: note: in definition of macro 'printk_ratelimited'
> > printk(fmt, ##__VA_ARGS__); \
> > ^~~
> > include/linux/kern_levels.h:12:22: note: in expansion of macro 'KERN_SOH'
> > #define KERN_WARNING KERN_SOH "4" /* warning conditions */
> > ^~~~~~~~
> > include/linux/printk.h:440:21: note: in expansion of macro 'KERN_WARNING'
> > printk_ratelimited(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
> > ^~~~~~~~~~~~
> > >> fs/notify/fanotify/fanotify.c:198:2: note: in expansion of macro 'pr_warn_ratelimited'
> > pr_warn_ratelimited("fanotify: failed to encode fid (fsid=%x.%x, "
> > ^~~~~~~~~~~~~~~~~~~
> > fs/notify/fanotify/fanotify.c:198:64: note: format string is defined here
> > pr_warn_ratelimited("fanotify: failed to encode fid (fsid=%x.%x, "
> > ~^
> > %lx
> >
> > vim +/pr_warn_ratelimited +198 fs/notify/fanotify/fanotify.c
> >
> > 154
> > 155 static int fanotify_encode_fid(struct fanotify_event *event,
> > 156 const struct path *path, gfp_t gfp)
> > 157 {
> > 158 struct fanotify_fid *fid = &event->fid;
> > 159 int dwords, bytes = 0;
> > 160 struct kstatfs stat;
> > 161 int err, type;
> > 162
> > 163 stat.f_fsid.val[0] = stat.f_fsid.val[1] = 0;
> > 164 fid->ext_fh = NULL;
> > 165 dwords = 0;
> > 166 err = -ENOENT;
> > 167 type = exportfs_encode_inode_fh(d_inode(path->dentry), NULL, &dwords,
> > 168 NULL);
> > 169 if (!dwords)
> > 170 goto out_err;
> > 171
> > 172 err = vfs_statfs(path, &stat);
> > 173 if (err)
> > 174 goto out_err;
> > 175
> > 176 bytes = dwords << 2;
> > 177 if (bytes > FANOTIFY_INLINE_FH_LEN) {
> > 178 /* Treat failure to allocate fh as failure to allocate event */
> > 179 err = -ENOMEM;
> > 180 fid->ext_fh = kmalloc(bytes, gfp);
> > 181 if (!fid->ext_fh)
> > 182 goto out_err;
> > 183 }
> > 184
> > 185 type = exportfs_encode_inode_fh(d_inode(path->dentry),
> > 186 fanotify_fid_fh(fid, bytes), &dwords,
> > 187 NULL);
> > 188 err = -EINVAL;
> > 189 if (!type || type == FILEID_INVALID || bytes != dwords << 2)
> > 190 goto out_err;
> > 191
> > 192 fid->fsid = stat.f_fsid;
> > 193 event->fh_len = bytes;
> > 194
> > 195 return type;
> > 196
> > 197 out_err:
> > > 198 pr_warn_ratelimited("fanotify: failed to encode fid (fsid=%x.%x, "
> > 199 "type=%d, bytes=%d, err=%i)\n",
> > 200 stat.f_fsid.val[0], stat.f_fsid.val[1],
> > 201 type, bytes, err);
> > 202 kfree(fid->ext_fh);
> > 203 fid->ext_fh = NULL;
> > 204 event->fh_len = 0;
> > 205
> > 206 return FILEID_INVALID;
> > 207 }
> > 208
> >
> > ---
> > 0-DAY kernel test infrastructure Open Source Technology Center
> > https://lists.01.org/pipermail/kbuild-all Intel Corporation
>
>
> --
> Jan Kara <jack@...e.com>
> SUSE Labs, CR
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