When attaching default groups (subdirs) of a new group (in mkdir() or
in configfs_register()), configfs recursively takes inode's mutexes
along the path from the parent of the new group to the default
subdirs. This is needed to ensure that the VFS will not race with
operations on these sub-dirs. This is safe for the following reasons:
- the VFS allows one to lock first an inode and second one of its
children (The lock subclasses for this pattern are respectively
I_MUTEX_PARENT and I_MUTEX_CHILD);
- from this rule any inode path can be recursively locked in
descending order as long as it stays under a single mountpoint and
does not follow symlinks.
Unfortunately lockdep does not know (yet?) how to handle such
recursion.
I've tried to use Peter Zijlstra's lock_set_subclass() helper to
upgrade i_mutexes from I_MUTEX_CHILD to I_MUTEX_PARENT when we know
that we might recursively lock some of their descendant, but this
usage does not seem to fit the purpose of lock_set_subclass() because
it leads to several i_mutex locked with subclass I_MUTEX_PARENT by
the same task.
>From inside configfs it is not possible to serialize those recursive
locking with a top-level one, because mkdir() and rmdir() are already
called with inodes locked by the VFS. So using some
mutex_lock_nest_lock() is not an option.
I am proposing two solutions:
1) one that wraps recursive mutex_lock()s with
lockdep_off()/lockdep_on().
2) (as suggested earlier by Peter Zijlstra) one that puts the
i_mutexes recursively locked in different classes based on their
depth from the top-level config_group created. This
induces an arbitrary limit (MAX_LOCK_DEPTH - 2 == 46) on the
nesting of configfs default groups whenever lockdep is activated
but this limit looks reasonably high. Unfortunately, this alos
isolates VFS operations on configfs default groups from the others
and thus lowers the chances to detect locking issues.
This patch implements solution 1).
Solution 2) looks better from lockdep's point of view, but fails with
configfs_depend_item(). This needs to rework the locking
scheme of configfs_depend_item() by removing the variable lock recursion
depth, and I think that it's doable thanks to the configfs_dirent_lock.
For now, let's stick to solution 1).
Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
It could happen that some limit has been set via quotactl() and in parallel
->mark_dirty() is called from another thread doing e.g. dquot_alloc_space(). In
such case ocfs2_write_dquot() must not try to sync the dquot because that needs
global quota lock but that ranks above transaction start.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Dropping of last reference to dentry lock is a complicated operation involving
dropping of reference to inode. This can get complicated and quota code in
particular needs to obtain some quota locks which leads to potential deadlock.
Thus we defer dropping of inode reference to ocfs2_wq.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
This essentially reverts commit 8edb08caf6.
It downgraded our mmap semaphore to a read-lock while mlocking pages, in
order to allow other threads (and external accesses like "ps" et al) to
walk the vma lists and take page faults etc. Which is a nice idea, but
the implementation does not work.
Because we cannot upgrade the lock back to a write lock without
releasing the mmap semaphore, the code had to release the lock entirely
and then re-take it as a writelock. However, that meant that the caller
possibly lost the vma chain that it was following, since now another
thread could come in and mmap/munmap the range.
The code tried to work around that by just looking up the vma again and
erroring out if that happened, but quite frankly, that was just a buggy
hack that doesn't actually protect against anything (the other thread
could just have replaced the vma with another one instead of totally
unmapping it).
The only way to downgrade to a read map _reliably_ is to do it at the
end, which is likely the right thing to do: do all the 'vma' operations
with the write-lock held, then downgrade to a read after completing them
all, and then do the "populate the newly mlocked regions" while holding
just the read lock. And then just drop the read-lock and return to user
space.
The (perhaps somewhat simpler) alternative is to just make all the
callers of mlock_vma_pages_range() know that the mmap lock got dropped,
and just re-grab the mmap semaphore if it needs to mlock more than one
vma region.
So we can do this "downgrade mmap sem while populating mlocked regions"
thing right, but the way it was done here was absolutely not correct.
Thus the revert, in the expectation that we will do it all correctly
some day.
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
generic-ipi: use per cpu data for single cpu ipi calls
cpumask: convert lib/smp_processor_id to new cpumask ops
signals, debug: fix BUG: using smp_processor_id() in preemptible code in print_fatal_signal()
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
hrtimer: prevent negative expiry value after clock_was_set()
hrtimers: allow the hot-unplugging of all cpus
hrtimers: increase clock min delta threshold while interrupt hanging
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, ds, bts: cleanup/fix DS configuration
ring-buffer: reset timestamps when ring buffer is reset
trace: set max latency variable to zero on default
trace: stop all recording to ring buffer on ftrace_dump
trace: print ftrace_dump at KERN_EMERG log level
ring_buffer: reset write when reserve buffer fail
tracing/function-graph-tracer: fix a regression while suspend to disk
ring-buffer: fix alignment problem
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86 setup: fix asm constraints in vesa_store_edid
xen: make sysfs files behave as their names suggest
x86: tone down mtrr_trim_uncached_memory() warning
x86: correct the CPUID pattern for MSR_IA32_MISC_ENABLE availability
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lrg/voltage-2.6:
leds: Fix bounds checking of wm8350->pmic.led
regulator: move bq24022 init back to module_init instead of subsys_initcall
Fix an off-by-two memory error in console selection.
The loop below goes from sel_start to sel_end (inclusive), so it writes
one more character. This one more character was added to the allocated
size (+1), but it was not multiplied by an UTF-8 multiplier.
This patch fixes a memory corruption when UTF-8 console is used and the
user selects a few characters, all of them 3-byte in UTF-8 (for example
a frame line).
When memory redzones are enabled, a redzone corruption is reported.
When they are not enabled, trashing of random memory occurs.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
igb: fix link reporting when using sgmii
igb: prevent skb_over panic w/ mtu smaller than 1K
igb: Fix DCA errors and do not use context index for 82576
ipv6: compile fix for ip6mr.c
packet: Avoid lock_sock in mmap handler
sfc: Replace stats_enabled flag with a disable count
sfc: SFX7101/SFT9001: Fix AN advertisements
sfc: SFT9001: Always enable XNP exchange on SFT9001 rev B
sfc: Update board info for hardware monitor on SFN4111T-R5 and later
sfc: Test for PHYXS faults whenever we cannot test link state bits
sfc: Reinitialise the PHY completely in case of a PHY or NIC reset
sfc: Fix post-reset MAC selection
sfc: SFN4111T: Fix GPIO sharing between I2C and FLASH_CFG_1
sfc: SFT9001: Fix speed reporting in 1G PHY loopback
sfc: SFX7101: Remove workaround for bad link training
sfc: SFT9001: Enable robust link training
sky2: fix hard hang with netconsoling and iface going up
The mmap_region() code would temporarily set the VM_ACCOUNT flag for
anonymous shared mappings just to inform shmem_zero_setup() that it
should enable accounting for the resulting shm object. It would then
clear the flag after calling ->mmap (for the /dev/zero case) or doing
shmem_zero_setup() (for the MAP_ANON case).
This just resulted in vma merge issues, but also made for just
unnecessary confusion. Use the already-existing VM_NORESERVE flag for
this instead, and let shmem_{zero|file}_setup() just figure it out from
that.
This also happens to make it obvious that the new DRI2 GEM layer uses a
non-reserving backing store for its object allocation - which is quite
possibly not intentional. But since I didn't want to change semantics
in this patch, I left it alone, and just updated the caller to use the
new flag semantics.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When using sgmii the link was not being properly passed up to the driver
from the underlying link management functions. This change corrects it so
that get_link_status is cleared when a link has been found.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
A panic has been observed with frame sizes smaller than 1K. This has been
root caused to the hardware spanning larger frames across multiple buffers
and then reporting the original frame size in the first descriptor. To
prevent this we can enable set the LPE bit which in turn will restrict
packet sizes to those set in the RLPML register.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
82576 was being incorrectly flagged as needing a context index. It does not as
each ring has it's own table of 2 contexts.
Driver was registering after registering the driver instead of the other way around.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv6/ip6mr.c: In function 'pim6_rcv':
net/ipv6/ip6mr.c:368: error: implicit declaration of function 'csum_ipv6_magic'
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Impact: fix potential miscompile (currently believed non-manifest)
As the comment explains, the VBE DDC call can clobber any register.
Tell the compiler about that fact.
Signed-off-by: Andreas Schwab <schwab@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
As the mmap handler gets called under mmap_sem, and we may grab
mmap_sem elsewhere under the socket lock to access user data, we
should avoid grabbing the socket lock in the mmap handler.
Since the only thing we care about in the mmap handler is for
pg_vec* to be invariant, i.e., to exclude packet_set_ring, we
can achieve this by simply using a new mutex.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Martin MOKREJŠ <mmokrejs@ribosome.natur.cuni.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently we use a spin-lock to serialise statistics fetches and also
to inhibit them for short periods of time, plus a flag to
enable/disable statistics fetches for longer periods of time, during
online reset. This was apparently insufficient to deal with the several
reasons for stats being disabled.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All 10Xpress PHYs require autonegotiation all the time; enforce this
in the set_settings() method and do not treat it as a workaround.
Remove claimed support for 100M HD mode since it is not supported by
current firmware.
Do not set speed override bits when AN is enabled, and do not use
register 1.49192 for AN configuration as it can override what we set
elsewhere.
Always set the AN selector bits to 1 (802.3).
Fix confusion between Next Page and Extended Next Page.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Joel Becker
Jan Kara
Linus Torvalds
Mikulas Patocka
Alexander Duyck
Dave Jones
Andreas Schwab
Herbert Xu
Ben Hutchings