Commits · 0cae60f91494e34a0c5391f1455f825d5849b05f · Kirill Smelkov / linux

01 Nov, 2013 2 commits

sysfs: rename sysfs_assoc_lock and explain what it's about · 0cae60f9

Tejun Heo authored Oct 30, 2013

sysfs_assoc_lock is an odd piece of locking.  In general, whoever owns
a kobject is responsible for synchronizing sysfs operations and sysfs
proper assumes that, for example, removal won't race with any other
operation; however, this doesn't work for symlinking because an entity
performing symlink doesn't usually own the target kobject and thus has
no control over its removal.

sysfs_assoc_lock synchronizes symlink operations against kobj->sd
disassociation so that symlink code doesn't end up dereferencing
already freed sysfs_dirent by racing with removal of the target
kobject.

This is quite obscure and the generic name of the lock and lack of
comments make it difficult to understand its role.  Let's rename it to
sysfs_symlink_target_lock and add comments explaining what's going on.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

0cae60f9

sysfs: use generic_file_llseek() for sysfs_file_operations · 044e3bc3

Tejun Heo authored Nov 01, 2013

13c589d5 ("sysfs: use seq_file when reading regular files")
converted regular sysfs files to use seq_file.  The commit substituted
generic_file_llseek() with seq_lseek() for llseek implementation.

Before the change, all regular sysfs files were allowed to seek to any
position in [0, PAGE_SIZE] as the file size is always PAGE_SIZE and
generic_file_llseek() allows any seeking inside the range under file
size; however, seq_lseek()'s behavior is different.  It traverses the
output by repeatedly invoking ->show() until it reaches the target
offset or traversal indicates EOF.  As seq_files are fully dynamic and
may not end at all, it doesn't support seeking from the end
(SEEK_END).

Apparently, there are userland tools which uses SEEK_END to discover
the buffer size to use and the switch to seq_lseek() disturbs them as
SEEK_END fails with -EINVAL.

The only benefits of using seq_lseek() instead of
generic_file_llseek() are

* Early failure.  If traversing to certain file position should fail,
  seq_lseek() will report such failures on lseek(2) instead of the
  following read/write operations.

* EOF detection.  While SEEK_END is not supported, SEEK_SET/CUR +
  large offset can be used to detect eof - eof at the time of the seek
  anyway as the file size may change dynamically.

Both aren't necessary for sysfs or prospect kernfs users.  Revert to
genefic_file_llseek() and preserve the original behavior.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Link: https://lkml.kernel.org/r/20131031114358.GA5551@osirisTested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

044e3bc3

30 Oct, 2013 1 commit

sysfs: return correct error code on unimplemented mmap() · 1c1365e3

Vladimir Zapolskiy authored Oct 30, 2013

Both POSIX.1-2008 and Linux Programmer's Manual have a dedicated return
error code for a case, when a file doesn't support mmap(), it's ENODEV.

This change replaces overloaded EINVAL with ENODEV in a situation
described above for sysfs binary files.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1c1365e3

29 Oct, 2013 7 commits

mdio_bus: convert bus code to use dev_groups · 4192c749

Greg Kroah-Hartman authored Oct 06, 2013

The dev_attrs field of struct bus_type is going away soon, dev_groups
should be used instead.  This converts the MDIO bus code to use the
correct field.

Cc: David S. Miller <davem@davemloft.net>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Nick Bowler <nbowler@elliptictech.com>
Cc: <netdev@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4192c749

device: Make dev_WARN/dev_WARN_ONCE print device as well as driver name · 3eae1367

Bjorn Helgaas authored Oct 24, 2013

dev_WARN() and dev_WARN_ONCE() are annoying because (1) they include
only the driver name, not the device name, and (2) they print a spurious
newline in the middle.  This results in messages like this that are less
useful than they should be:

  [   40.094995] Device pcieport
  disabling already-disabled device

This patch makes them work more like dev_printk().
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>