Pull v9fs update from Eric Van Hensbergen. * tag 'for-linus-merge-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs: 9P: Fix race between p9_write_work() and p9_fd_request() 9P: Fix race in p9_write_work() 9P: fix test at the end of p9_write_work() 9P: Fix race in p9_read_work() 9p: don't use __getname/__putname for uname/aname net/9p: Check errno validity fs/9p: avoid debug OOPS when reading a long symlink
Race scenario:
thread A thread B
p9_write_work() p9_fd_request()
if (list_empty
(&m->unsent_req_list))
...
spin_lock(&client->lock);
req->status = REQ_STATUS_UNSENT;
list_add_tail(..., &m->unsent_req_list);
spin_unlock(&client->lock);
....
if (n & POLLOUT &&
!test_and_set_bit(Wworksched, &m->wsched)
schedule_work(&m->wq);
--> not done because Wworksched is set
clear_bit(Wworksched, &m->wsched);
return;
--> nobody will take care of sending the new request.
This is not very likely to happen though, because p9_write_work()
being called with an empty unsent_req_list is not frequent.
But this also means that taking the lock earlier will not be costly.
Signed-off-by: Simon Derr <simon.derr@bull.net>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Pull vfs update from Al Viro:
- big one - consolidation of descriptor-related logics; almost all of
that is moved to fs/file.c
(BTW, I'm seriously tempted to rename the result to fd.c. As it is,
we have a situation when file_table.c is about handling of struct
file and file.c is about handling of descriptor tables; the reasons
are historical - file_table.c used to be about a static array of
struct file we used to have way back).
A lot of stray ends got cleaned up and converted to saner primitives,
disgusting mess in android/binder.c is still disgusting, but at least
doesn't poke so much in descriptor table guts anymore. A bunch of
relatively minor races got fixed in process, plus an ext4 struct file
leak.
- related thing - fget_light() partially unuglified; see fdget() in
there (and yes, it generates the code as good as we used to have).
- also related - bits of Cyrill's procfs stuff that got entangled into
that work; _not_ all of it, just the initial move to fs/proc/fd.c and
switch of fdinfo to seq_file.
- Alex's fs/coredump.c spiltoff - the same story, had been easier to
take that commit than mess with conflicts. The rest is a separate
pile, this was just a mechanical code movement.
- a few misc patches all over the place. Not all for this cycle,
there'll be more (and quite a few currently sit in akpm's tree)."
Fix up trivial conflicts in the android binder driver, and some fairly
simple conflicts due to two different changes to the sock_alloc_file()
interface ("take descriptor handling from sock_alloc_file() to callers"
vs "net: Providing protocol type via system.sockprotoname xattr of
/proc/PID/fd entries" adding a dentry name to the socket)
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (72 commits)
MAX_LFS_FILESIZE should be a loff_t
compat: fs: Generic compat_sys_sendfile implementation
fs: push rcu_barrier() from deactivate_locked_super() to filesystems
btrfs: reada_extent doesn't need kref for refcount
coredump: move core dump functionality into its own file
coredump: prevent double-free on an error path in core dumper
usb/gadget: fix misannotations
fcntl: fix misannotations
ceph: don't abuse d_delete() on failure exits
hypfs: ->d_parent is never NULL or negative
vfs: delete surplus inode NULL check
switch simple cases of fget_light to fdget
new helpers: fdget()/fdput()
switch o2hb_region_dev_write() to fget_light()
proc_map_files_readdir(): don't bother with grabbing files
make get_file() return its argument
vhost_set_vring(): turn pollstart/pollstop into bool
switch prctl_set_mm_exe_file() to fget_light()
switch xfs_find_handle() to fget_light()
switch xfs_swapext() to fget_light()
...
Both modular callers of sock_map_fd() had been buggy; sctp one leaks descriptor and file if copy_to_user() fails, 9p one shouldn't be exposing file in the descriptor table at all. Switch both to sock_alloc_file(), export it, unexport sock_map_fd() and make it static. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
See previous commit about p9_read_work() for details. This fixes a similar race between p9_write_work() and p9_poll_mux() Signed-off-by: Simon Derr <simon.derr@bull.net> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
At the end of p9_write_work() we want to test if there is still data to send. This means: - either the current request still has data to send (wsize != 0) - or there are requests in the unsent queue Signed-off-by: Simon Derr <simon.derr@bull.net> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Race scenario between p9_read_work() and p9_poll_mux()
Data arrive, Rworksched is set, p9_read_work() is called.
thread A thread B
p9_read_work()
.
reads data
.
checks if new data ready. No.
.
gets preempted
.
More data arrive, p9_poll_mux() is called. .
.
.
p9_poll_mux() .
.
if (!test_and_set_bit(Rworksched, .
&m->wsched)) { .
schedule_work(&m->rq); .
} .
.
-> does not schedule work because .
Rworksched is set .
.
clear_bit(Rworksched, &m->wsched);
return;
No work has been scheduled, and yet data are waiting.
Currently p9_read_work() checks if there is data to read,
and if not, it clears Rworksched.
I think it should clear Rworksched first, and then check if there is data to read.
Signed-off-by: Simon Derr <simon.derr@bull.net>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
flush[_delayed]_work_sync() are now spurious. Mark them deprecated and convert all users to flush[_delayed]_work(). If you're cc'd and wondering what's going on: Now all workqueues are non-reentrant and the regular flushes guarantee that the work item is not pending or running on any CPU on return, so there's no reason to use the sync flushes at all and they're going away. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Russell King <linux@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ian Campbell <ian.campbell@citrix.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mattia Dongili <malattia@linux.it> Cc: Kent Yoder <key@linux.vnet.ibm.com> Cc: David Airlie <airlied@linux.ie> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Karsten Keil <isdn@linux-pingi.de> Cc: Bryan Wu <bryan.wu@canonical.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Alasdair Kergon <agk@redhat.com> Cc: Mauro Carvalho Chehab <mchehab@infradead.org> Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de> Cc: David Woodhouse <dwmw2@infradead.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: linux-wireless@vger.kernel.org Cc: Anton Vorontsov <cbou@mail.ru> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Takashi Iwai <tiwai@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Petr Vandrovec <petr@vandrovec.name> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Avi Kivity <avi@redhat.com>
Use of "unsigned int" is preferred to bare "unsigned" in net tree. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Reduce object size by deduplicating formats. Use vsprintf extension %pV. Rename P9_DPRINTK uses to p9_debug, align arguments. Add function for _p9_debug and macro to add __func__. Add missing "\n"s to p9_debug uses. Remove embedded function names as p9_debug adds it. Remove P9_EPRINTK macro and convert use to pr_<level>. Add and use pr_fmt and pr_<level>. $ size fs/9p/built-in.o* text data bss dec hex filename 62133 984 16000 79117 1350d fs/9p/built-in.o.new 67342 984 16928 85254 14d06 fs/9p/built-in.o.old $ size net/9p/built-in.o* text data bss dec hex filename 88792 4148 22024 114964 1c114 net/9p/built-in.o.new 94072 4148 23232 121452 1da6c net/9p/built-in.o.old Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>