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commit 75646e758a0ecbed5024454507d5be5b9ea9dcbf upstream.
Some machines (eg. Lenovo Z480) ECs are not stable during boot up
and causes battery driver fails to be loaded due to failure of getting
battery information from EC sometimes. After several retries, the
operation will work. This patch is to retry to get battery information 5
times if the first try fails.
[ backport to 3.14.5: removed second parameter in acpi_battery_update(),
introduced by the commit 9e50bc14a7f58b5d8a55973b2d69355852ae2dae (ACPI /
battery: Accelerate battery resume callback)]
[naszar <naszar@ya.ru>: backport to 3.14.5]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=75581
Reported-and-tested-by: naszar <naszar@ya.ru>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit c81c8a1eeede61e92a15103748c23d100880cc8a upstream.
In __ioremap_caller() (the guts of ioremap), we loop over the range of
pfns being remapped and checks each one individually with page_is_ram().
For large ioremaps, this can be very slow. For example, we have a
device with a 256 GiB PCI BAR, and ioremapping this BAR can take 20+
seconds -- sometimes long enough to trigger the soft lockup detector!
Internally, page_is_ram() calls walk_system_ram_range() on a single
page. Instead, we can make a single call to walk_system_ram_range()
from __ioremap_caller(), and do our further checks only for any RAM
pages that we find. For the common case of MMIO, this saves an enormous
amount of work, since the range being ioremapped doesn't intersect
system RAM at all.
With this change, ioremap on our 256 GiB BAR takes less than 1 second.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Link: http://lkml.kernel.org/r/1399054721-1331-1-git-send-email-roland@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit df9e4d1c39c472cb44d81ab2ed2db503fc486e3b upstream.
Signed-off-by: Lennox Wu <lennox.wu@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 5fbbf8a1a93452b26e7791cf32cefce62b0a480b upstream.
The modifications include:
1. Kconfig of Score: we don't support ioremap
2. Missed headfile including
3. There are some errors in other people's commit not checked by us, we fix it now
3.1 arch/score/kernel/entry.S: wrong instructions
3.2 arch/score/kernel/process.c : just some typos
Signed-off-by: Lennox Wu <lennox.wu@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1ed62ca648557b884d117a4a8bbcf2ae4e2d1153 upstream.
Signed-off-by: Lennox Wu <lennox.wu@gmail.com>
Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ae49b83dcacfb69e22092cab688c415c2f2d870c upstream.
Generate mandatory global variables _sdata in file vmlinux.lds.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 27e35715df54cbc4f2d044f681802ae30479e7fb upstream.
When the rtmutex fast path is enabled the slow unlock function can
create the following situation:
spin_lock(foo->m->wait_lock);
foo->m->owner = NULL;
rt_mutex_lock(foo->m); <-- fast path
free = atomic_dec_and_test(foo->refcnt);
rt_mutex_unlock(foo->m); <-- fast path
if (free)
kfree(foo);
spin_unlock(foo->m->wait_lock); <--- Use after free.
Plug the race by changing the slow unlock to the following scheme:
while (!rt_mutex_has_waiters(m)) {
/* Clear the waiters bit in m->owner */
clear_rt_mutex_waiters(m);
owner = rt_mutex_owner(m);
spin_unlock(m->wait_lock);
if (cmpxchg(m->owner, owner, 0) == owner)
return;
spin_lock(m->wait_lock);
}
So in case of a new waiter incoming while the owner tries the slow
path unlock we have two situations:
unlock(wait_lock);
lock(wait_lock);
cmpxchg(p, owner, 0) == owner
mark_rt_mutex_waiters(lock);
acquire(lock);
Or:
unlock(wait_lock);
lock(wait_lock);
mark_rt_mutex_waiters(lock);
cmpxchg(p, owner, 0) != owner
enqueue_waiter();
unlock(wait_lock);
lock(wait_lock);
wakeup_next waiter();
unlock(wait_lock);
lock(wait_lock);
acquire(lock);
If the fast path is disabled, then the simple
m->owner = NULL;
unlock(m->wait_lock);
is sufficient as all access to m->owner is serialized via
m->wait_lock;
Also document and clarify the wakeup_next_waiter function as suggested
by Oleg Nesterov.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140611183852.937945560@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 3d5c9340d1949733eb37616abd15db36aef9a57c upstream.
Even in the case when deadlock detection is not requested by the
caller, we can detect deadlocks. Right now the code stops the lock
chain walk and keeps the waiter enqueued, even on itself. Silly not to
yell when such a scenario is detected and to keep the waiter enqueued.
Return -EDEADLK unconditionally and handle it at the call sites.
The futex calls return -EDEADLK. The non futex ones dequeue the
waiter, throw a warning and put the task into a schedule loop.
Tagged for stable as it makes the code more robust.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Brad Mouring <bmouring@ni.com>
Link: http://lkml.kernel.org/r/20140605152801.836501969@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 82084984383babe728e6e3c9a8e5c46278091315 upstream.
When we walk the lock chain, we drop all locks after each step. So the
lock chain can change under us before we reacquire the locks. That's
harmless in principle as we just follow the wrong lock path. But it
can lead to a false positive in the dead lock detection logic:
T0 holds L0
T0 blocks on L1 held by T1
T1 blocks on L2 held by T2
T2 blocks on L3 held by T3
T4 blocks on L4 held by T4
Now we walk the chain
lock T1 -> lock L2 -> adjust L2 -> unlock T1 ->
lock T2 -> adjust T2 -> drop locks
T2 times out and blocks on L0
Now we continue:
lock T2 -> lock L0 -> deadlock detected, but it's not a deadlock at all.
Brad tried to work around that in the deadlock detection logic itself,
but the more I looked at it the less I liked it, because it's crystal
ball magic after the fact.
We actually can detect a chain change very simple:
lock T1 -> lock L2 -> adjust L2 -> unlock T1 -> lock T2 -> adjust T2 ->
next_lock = T2->pi_blocked_on->lock;
drop locks
T2 times out and blocks on L0
Now we continue:
lock T2 ->
if (next_lock != T2->pi_blocked_on->lock)
return;
So if we detect that T2 is now blocked on a different lock we stop the
chain walk. That's also correct in the following scenario:
lock T1 -> lock L2 -> adjust L2 -> unlock T1 -> lock T2 -> adjust T2 ->
next_lock = T2->pi_blocked_on->lock;
drop locks
T3 times out and drops L3
T2 acquires L3 and blocks on L4 now
Now we continue:
lock T2 ->
if (next_lock != T2->pi_blocked_on->lock)
return;
We don't have to follow up the chain at that point, because T2
propagated our priority up to T4 already.
[ Folded a cleanup patch from peterz ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Brad Mouring <bmouring@ni.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140605152801.930031935@linutronix.de
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 397335f004f41e5fcf7a795e94eb3ab83411a17c upstream.
The current deadlock detection logic does not work reliably due to the
following early exit path:
/*
* Drop out, when the task has no waiters. Note,
* top_waiter can be NULL, when we are in the deboosting
* mode!
*/
if (top_waiter && (!task_has_pi_waiters(task) ||
top_waiter != task_top_pi_waiter(task)))
goto out_unlock_pi;
So this not only exits when the task has no waiters, it also exits
unconditionally when the current waiter is not the top priority waiter
of the task.
So in a nested locking scenario, it might abort the lock chain walk
and therefor miss a potential deadlock.
Simple fix: Continue the chain walk, when deadlock detection is
enabled.
We also avoid the whole enqueue, if we detect the deadlock right away
(A-A). It's an optimization, but also prevents that another waiter who
comes in after the detection and before the task has undone the damage
observes the situation and detects the deadlock and returns
-EDEADLOCK, which is wrong as the other task is not in a deadlock
situation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/20140522031949.725272460@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8b8b36834d0fff67fc8668093f4312dd04dcf21d upstream.
The per_cpu buffers are created one per possible CPU. But these do
not mean that those CPUs are online, nor do they even exist.
With the addition of the ring buffer polling, it assumes that the
caller polls on an existing buffer. But this is not the case if
the user reads trace_pipe from a CPU that does not exist, and this
causes the kernel to crash.
Simple fix is to check the cpu against buffer bitmask against to see
if the buffer was allocated or not and return -ENODEV if it is
not.
More updates were done to pass the -ENODEV back up to userspace.
Link: http://lkml.kernel.org/r/5393DB61.6060707@oracle.com
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 0986c1a55ca64b44ee126a2f719a6e9f28cbe0ed upstream.
When we set the valid bit on invalid GART entries they are
loaded into the TLB when an adjacent entry is loaded. This
poisons the TLB with invalid entries which are sometimes
not correctly removed on TLB flush.
For stable inclusion the patch probably needs to be modified a bit.
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 6abafb78f9881b4891baf74ab4e9f090ae45230e upstream.
Fixes hangs on driver load on some cards.
bug:
https://bugs.freedesktop.org/show_bug.cgi?id=76998
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 5dd214248f94d430d70e9230bda72f2654ac88a8 upstream.
The mount manpage says of the max_batch_time option,
This optimization can be turned off entirely
by setting max_batch_time to 0.
But the code doesn't do that. So fix the code to do
that.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ae0f78de2c43b6fadd007c231a352b13b5be8ed2 upstream.
Make it clear that values printed are times, and that it is error
since last fsck. Also add note about fsck version required.
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 61c219f5814277ecb71d64cb30297028d6665979 upstream.
The first time that we allocate from an uninitialized inode allocation
bitmap, if the block allocation bitmap is also uninitalized, we need
to get write access to the block group descriptor before we start
modifying the block group descriptor flags and updating the free block
count, etc. Otherwise, there is the potential of a bad journal
checksum (if journal checksums are enabled), and of the file system
becoming inconsistent if we crash at exactly the wrong time.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 10f1d5d111e8aed46a0f1179faf9a3cf422f689e upstream.
There's a race condition between the atomic_dec_and_test(&io->count)
in dec_count() and the waking of the sync_io() thread. If the thread
is spuriously woken immediately after the decrement it may exit,
making the on stack io struct invalid, yet the dec_count could still
be using it.
Fix this race by using a completion in sync_io() and dec_count().
Reported-by: Minfei Huang <huangminfei@ucloud.cn>
Signed-off-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit affb1aff300ddee54df307812b38f166e8a865ef upstream.
Starting with Win8, we have implemented several optimizations to improve the
scalability and performance of the VMBUS transport between the Host and the
Guest. Some of the non-performance critical services cannot leverage these
optimization since they only read and process one message at a time.
Make adjustments to the callback dispatch code to account for the way
non-performance critical drivers handle reading of the channel.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 15ebb05248d025534773c9ef64915bd888f04e4b upstream.
The control register is at offset 0x10, not 0x0. This is wreckaged
since commit 5df33a62c (SPEAr: Switch to common clock framework).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit fa2ec3ea10bd377f9d55772b1dab65178425a1a2 upstream.
include/linux/sched.h implements TASK_SIZE_OF as TASK_SIZE if it
is not set by the architecture headers. TASK_SIZE uses the
current task to determine the size of the virtual address space.
On a 64-bit kernel this will cause reading /proc/pid/pagemap of a
64-bit process from a 32-bit process to return EOF when it reads
past 0xffffffff.
Implement TASK_SIZE_OF exactly the same as TASK_SIZE with
test_tsk_thread_flag instead of test_thread_flag.
Signed-off-by: Colin Cross <ccross@android.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit cfe82d4f45c7cc39332a2be7c4c1d3bf279bbd3d upstream.
Byte-to-bit-count computation is only partly converted to big-endian and is
mixing in CPU-endian values. Problem was noticed by sparce with warning:
CHECK arch/x86/crypto/sha512_ssse3_glue.c
arch/x86/crypto/sha512_ssse3_glue.c:144:19: warning: restricted __be64 degrades to integer
arch/x86/crypto/sha512_ssse3_glue.c:144:17: warning: incorrect type in assignment (different base types)
arch/x86/crypto/sha512_ssse3_glue.c:144:17: expected restricted __be64 <noident>
arch/x86/crypto/sha512_ssse3_glue.c:144:17: got unsigned long long
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 5a90af67c2126fe1d04ebccc1f8177e6ca70d3a9 upstream.
Since commtit 8a7b1227e303 (cpufreq: davinci: move cpufreq driver to
drivers/cpufreq) this added dependancy only for CONFIG_ARCH_DAVINCI_DA850
where as davinci_cpufreq_init() call is used by all davinci platform.
This patch fixes following build error:
arch/arm/mach-davinci/built-in.o: In function `davinci_init_late':
:(.init.text+0x928): undefined reference to `davinci_cpufreq_init'
make: *** [vmlinux] Error 1
Fixes: 8a7b1227e303 (cpufreq: davinci: move cpufreq driver to drivers/cpufreq)
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit b50a6c584bb47b370f84bfd746770c0bbe7129b7 upstream.
On POWER8 when switching to a KVM guest we set bits in MMCR2 to freeze
the PMU counters. Aside from on boot they are then never reset,
resulting in stuck perf counters for any user in the guest or host.
We now set MMCR2 to 0 whenever enabling the PMU, which provides a sane
state for perf to use the PMU counters under either the guest or the
host.
This was manifesting as a bug with ppc64_cpu --frequency:
$ sudo ppc64_cpu --frequency
WARNING: couldn't run on cpu 0
WARNING: couldn't run on cpu 8
...
WARNING: couldn't run on cpu 144
WARNING: couldn't run on cpu 152
min: 18446744073.710 GHz (cpu -1)
max: 0.000 GHz (cpu -1)
avg: 0.000 GHz
The command uses a perf counter to measure CPU cycles over a fixed
amount of time, in order to approximate the frequency of the machine.
The counters were returning zero once a guest was started, regardless of
weather it was still running or had been shut down.
By dumping the value of MMCR2, it was observed that once a guest is
running MMCR2 is set to 1s - which stops counters from running:
$ sudo sh -c 'echo p > /proc/sysrq-trigger'
CPU: 0 PMU registers, ppmu = POWER8 n_counters = 6
PMC1: 5b635e38 PMC2: 00000000 PMC3: 00000000 PMC4: 00000000
PMC5: 1bf5a646 PMC6: 5793d378 PMC7: deadbeef PMC8: deadbeef
MMCR0: 0000000080000000 MMCR1: 000000001e000000 MMCRA: 0000040000000000
MMCR2: fffffffffffffc00 EBBHR: 0000000000000000
EBBRR: 0000000000000000 BESCR: 0000000000000000
SIAR: 00000000000a51cc SDAR: c00000000fc40000 SIER: 0000000001000000
This is done unconditionally in book3s_hv_interrupts.S upon entering the
guest, and the original value is only save/restored if the host has
indicated it was using the PMU. This is okay, however the user of the
PMU needs to ensure that it is in a defined state when it starts using
it.
Fixes: e05b9b9e5c10 ("powerpc/perf: Power8 PMU support")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 4d9690dd56b0d18f2af8a9d4a279cb205aae3345 upstream.
Instead of separate bits for every POWER8 PMU feature, have a single one
for v2.07 of the architecture.
This saves us adding a MMCR2 define for a future patch.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f56029410a13cae3652d1f34788045c40a13ffc7 upstream.
We are seeing a lot of PMU warnings on POWER8:
Can't find PMC that caused IRQ
Looking closer, the active PMC is 0 at this point and we took a PMU
exception on the transition from negative to 0. Some versions of POWER8
have an issue where they edge detect and not level detect PMC overflows.
A number of places program the PMC with (0x80000000 - period_left),
where period_left can be negative. We can either fix all of these or
just ensure that period_left is always >= 1.
This patch takes the second option.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 867f9d463b82462793ea4610e748be0b04b37fc7 upstream.
The recently merged change (in v3.14-rc6) to ACPI resource detection
(below) causes all zero length ACPI resources to be elided from the
table:
commit b355cee88e3b1a193f0e9a81db810f6f83ad728b
Author: Zhang Rui <rui.zhang@intel.com>
Date: Thu Feb 27 11:37:15 2014 +0800
ACPI / resources: ignore invalid ACPI device resources
This change has caused a regression in (at least) serial port detection
for a number of machines (see LP#1313981 [1]). These seem to represent
their IO regions (presumably incorrectly) as a zero length region.
Reverting the above commit restores these serial devices.
Only elide zero length resources which lie at address 0.
Fixes: b355cee88e3b (ACPI / resources: ignore invalid ACPI device resources)
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit c024044d4da2c9c3b32933b4235df1e409293b84 upstream.
The module test script for the adm1021 driver exposes a cache problem
when writing temperature limits. temp_min and temp_max are expected
to be stored in milli-degrees C but are stored in degrees C.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1035a9e3e9c76b64a860a774f5b867d28d34acc2 upstream.
Writing to fanX_div does not clear the cache. As a result, reading
from fanX_div may return the old value for up to two seconds
after writing a new value.
This patch ensures the fan_div cache is updated in set_fan_div().
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 145e74a4e5022225adb84f4e5d4fff7938475c35 upstream.
Upper limit for write operations to temperature limit registers
was clamped to a fractional value. However, limit registers do
not support fractional values. As a result, upper limits of 127.5
degrees C or higher resulted in a rounded limit of 128 degrees C.
Since limit registers are signed, this was stored as -128 degrees C.
Clamp limits to (-55, +127) degrees C to solve the problem.
Value on writes to auto_temp[12]_min and auto_temp[12]_max were not
clamped at all, but masked. As a result, out-of-range writes resulted
in a more or less arbitrary limit. Clamp those attributes to (0, 127)
degrees C for more predictable results.
Cc: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit df86754b746e9a0ff6f863f690b1c01d408e3cdc upstream.
temp2_input should not be writable, fix it.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 5a6024f1604eef119cf3a6fa413fe0261a81a8f3 upstream.
When hot-adding and onlining CPU, kernel panic occurs, showing following
call trace.
BUG: unable to handle kernel paging request at 0000000000001d08
IP: [<ffffffff8114acfd>] __alloc_pages_nodemask+0x9d/0xb10
PGD 0
Oops: 0000 [#1] SMP
...
Call Trace:
[<ffffffff812b8745>] ? cpumask_next_and+0x35/0x50
[<ffffffff810a3283>] ? find_busiest_group+0x113/0x8f0
[<ffffffff81193bc9>] ? deactivate_slab+0x349/0x3c0
[<ffffffff811926f1>] new_slab+0x91/0x300
[<ffffffff815de95a>] __slab_alloc+0x2bb/0x482
[<ffffffff8105bc1c>] ? copy_process.part.25+0xfc/0x14c0
[<ffffffff810a3c78>] ? load_balance+0x218/0x890
[<ffffffff8101a679>] ? sched_clock+0x9/0x10
[<ffffffff81105ba9>] ? trace_clock_local+0x9/0x10
[<ffffffff81193d1c>] kmem_cache_alloc_node+0x8c/0x200
[<ffffffff8105bc1c>] copy_process.part.25+0xfc/0x14c0
[<ffffffff81114d0d>] ? trace_buffer_unlock_commit+0x4d/0x60
[<ffffffff81085a80>] ? kthread_create_on_node+0x140/0x140
[<ffffffff8105d0ec>] do_fork+0xbc/0x360
[<ffffffff8105d3b6>] kernel_thread+0x26/0x30
[<ffffffff81086652>] kthreadd+0x2c2/0x300
[<ffffffff81086390>] ? kthread_create_on_cpu+0x60/0x60
[<ffffffff815f20ec>] ret_from_fork+0x7c/0xb0
[<ffffffff81086390>] ? kthread_create_on_cpu+0x60/0x60
In my investigation, I found the root cause is wq_numa_possible_cpumask.
All entries of wq_numa_possible_cpumask is allocated by
alloc_cpumask_var_node(). And these entries are used without initializing.
So these entries have wrong value.
When hot-adding and onlining CPU, wq_update_unbound_numa() is called.
wq_update_unbound_numa() calls alloc_unbound_pwq(). And alloc_unbound_pwq()
calls get_unbound_pool(). In get_unbound_pool(), worker_pool->node is set
as follow:
3592 /* if cpumask is contained inside a NUMA node, we belong to that node */
3593 if (wq_numa_enabled) {
3594 for_each_node(node) {
3595 if (cpumask_subset(pool->attrs->cpumask,
3596 wq_numa_possible_cpumask[node])) {
3597 pool->node = node;
3598 break;
3599 }
3600 }
3601 }
But wq_numa_possible_cpumask[node] does not have correct cpumask. So, wrong
node is selected. As a result, kernel panic occurs.
By this patch, all entries of wq_numa_possible_cpumask are allocated by
zalloc_cpumask_var_node to initialize them. And the panic disappeared.
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: bce903809ab3 ("workqueue: add wq_numa_tbl_len and wq_numa_possible_cpumask[]")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 391acf970d21219a2a5446282d3b20eace0c0d7a upstream.
When runing with the kernel(3.15-rc7+), the follow bug occurs:
[ 9969.258987] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:586
[ 9969.359906] in_atomic(): 1, irqs_disabled(): 0, pid: 160655, name: python
[ 9969.441175] INFO: lockdep is turned off.
[ 9969.488184] CPU: 26 PID: 160655 Comm: python Tainted: G A 3.15.0-rc7+ #85
[ 9969.581032] Hardware name: FUJITSU-SV PRIMEQUEST 1800E/SB, BIOS PRIMEQUEST 1000 Series BIOS Version 1.39 11/16/2012
[ 9969.706052] ffffffff81a20e60 ffff8803e941fbd0 ffffffff8162f523 ffff8803e941fd18
[ 9969.795323] ffff8803e941fbe0 ffffffff8109995a ffff8803e941fc58 ffffffff81633e6c
[ 9969.884710] ffffffff811ba5dc ffff880405c6b480 ffff88041fdd90a0 0000000000002000
[ 9969.974071] Call Trace:
[ 9970.003403] [<ffffffff8162f523>] dump_stack+0x4d/0x66
[ 9970.065074] [<ffffffff8109995a>] __might_sleep+0xfa/0x130
[ 9970.130743] [<ffffffff81633e6c>] mutex_lock_nested+0x3c/0x4f0
[ 9970.200638] [<ffffffff811ba5dc>] ? kmem_cache_alloc+0x1bc/0x210
[ 9970.272610] [<ffffffff81105807>] cpuset_mems_allowed+0x27/0x140
[ 9970.344584] [<ffffffff811b1303>] ? __mpol_dup+0x63/0x150
[ 9970.409282] [<ffffffff811b1385>] __mpol_dup+0xe5/0x150
[ 9970.471897] [<ffffffff811b1303>] ? __mpol_dup+0x63/0x150
[ 9970.536585] [<ffffffff81068c86>] ? copy_process.part.23+0x606/0x1d40
[ 9970.613763] [<ffffffff810bf28d>] ? trace_hardirqs_on+0xd/0x10
[ 9970.683660] [<ffffffff810ddddf>] ? monotonic_to_bootbased+0x2f/0x50
[ 9970.759795] [<ffffffff81068cf0>] copy_process.part.23+0x670/0x1d40
[ 9970.834885] [<ffffffff8106a598>] do_fork+0xd8/0x380
[ 9970.894375] [<ffffffff81110e4c>] ? __audit_syscall_entry+0x9c/0xf0
[ 9970.969470] [<ffffffff8106a8c6>] SyS_clone+0x16/0x20
[ 9971.030011] [<ffffffff81642009>] stub_clone+0x69/0x90
[ 9971.091573] [<ffffffff81641c29>] ? system_call_fastpath+0x16/0x1b
The cause is that cpuset_mems_allowed() try to take
mutex_lock(&callback_mutex) under the rcu_read_lock(which was hold in
__mpol_dup()). And in cpuset_mems_allowed(), the access to cpuset is
under rcu_read_lock, so in __mpol_dup, we can reduce the rcu_read_lock
protection region to protect the access to cpuset only in
current_cpuset_is_being_rebound(). So that we can avoid this bug.
This patch is a temporary solution that just addresses the bug
mentioned above, can not fix the long-standing issue about cpuset.mems
rebinding on fork():
"When the forker's task_struct is duplicated (which includes
->mems_allowed) and it races with an update to cpuset_being_rebound
in update_tasks_nodemask() then the task's mems_allowed doesn't get
updated. And the child task's mems_allowed can be wrong if the
cpuset's nodemask changes before the child has been added to the
cgroup's tasklist."
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit bddbceb688c6d0decaabc7884fede319d02f96c8 upstream.
Uevents are suppressed during attributes registration, but never
restored, so kobject_uevent() does nothing.
Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 226223ab3c4118ddd10688cc2c131135848371ab
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit eadcc7208a2237016be7bdff4551ba7614da85c8 upstream.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d8279a40e50ad55539780aa617a32a53d7f0953e upstream.
This adds support for Infineon TriBoard TC1798 [1]. Only interface 1
is used as serial line (see [2], Figure 8-6).
[1] http://www.infineon.com/cms/de/product/microcontroller/development-tools-software-and-kits/tricore-tm-development-tools-software-and-kits/starterkits-and-evaluation-boards/starter-kit-tc1798/channel.html?channel=db3a304333b8a7ca0133cfa3d73e4268
[2] http://www.infineon.com/dgdl/TriBoardManual-TC1798-V10.pdf?folderId=db3a304412b407950112b409ae7c0343&fileId=db3a304333b8a7ca0133cfae99fe426a
Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz>
Cc: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 5a7fbe7e9ea0b1b9d7ffdba64db1faa3a259164c upstream.
This patch adds PID 0x0003 to the VID 0x128d (Testo). At least the
Testo 435-4 uses this, likely other gear as well.
Signed-off-by: Bert Vermeulen <bert@biot.com>
Cc: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit b9326057a3d8447f5d2e74a7b521ccf21add2ec0 upstream.
Corsair USB Dongles are shipped with Corsair AXi series PSUs.
These are cp210x serial usb devices, so make driver detect these.
I have a program, that can get information from these PSUs.
Tested with 2 different dongles shipped with Corsair AX860i and
AX1200i units.
Signed-off-by: Andras Kovacs <andras@sth.sze.hu>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 3d28bd840b2d3981cd28caf5fe1df38f1344dd60 upstream.
Add ID of the Telewell 4G v2 hardware to option driver to get legacy
serial interface working
Signed-off-by: Bernd Wachter <bernd.wachter@jolla.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d05f0cdcbe6388723f1900c549b4850360545201 upstream.
In v2.6.34 commit 9d8cebd4bcd7 ("mm: fix mbind vma merge problem")
introduced vma merging to mbind(), but it should have also changed the
convention of passing start vma from queue_pages_range() (formerly
check_range()) to new_vma_page(): vma merging may have already freed
that structure, resulting in BUG at mm/mempolicy.c:1738 and probably
worse crashes.
Fixes: 9d8cebd4bcd7 ("mm: fix mbind vma merge problem")
Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Tested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 4a705fef986231a3e7a6b1a6d3c37025f021f49f upstream.
There's a race between fork() and hugepage migration, as a result we try
to "dereference" a swap entry as a normal pte, causing kernel panic.
The cause of the problem is that copy_hugetlb_page_range() can't handle
"swap entry" family (migration entry and hwpoisoned entry) so let's fix
it.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit fd1232b214af43a973443aec6a2808f16ee5bf70 upstream.
This patch fixes I/O errors with the sym53c8xx_2 driver when the disk
returns QUEUE FULL status.
When the controller encounters an error (including QUEUE FULL or BUSY
status), it aborts all not yet submitted requests in the function
sym_dequeue_from_squeue.
This function aborts them with DID_SOFT_ERROR.
If the disk has full tag queue, the request that caused the overflow is
aborted with QUEUE FULL status (and the scsi midlayer properly retries
it until it is accepted by the disk), but the sym53c8xx_2 driver aborts
the following requests with DID_SOFT_ERROR --- for them, the midlayer
does just a few retries and then signals the error up to sd.
The result is that disk returning QUEUE FULL causes request failures.
The error was reproduced on 53c895 with COMPAQ BD03685A24 disk
(rebranded ST336607LC) with command queue 48 or 64 tags. The disk has
64 tags, but under some access patterns it return QUEUE FULL when there
are less than 64 pending tags. The SCSI specification allows returning
QUEUE FULL anytime and it is up to the host to retry.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit fbc6c4a13bbfb420eedfdb26a0a859f9c07e8a7b upstream.
Function unifb_mmap calls functions which are defined in linux/mm.h
and asm/pgtable.h
The related error (for unicore32 with unicore32_defconfig):
CC drivers/video/fbdev/fb-puv3.o
drivers/video/fbdev/fb-puv3.c: In function 'unifb_mmap':
drivers/video/fbdev/fb-puv3.c:646: error: implicit declaration of
function 'vm_iomap_memory'
drivers/video/fbdev/fb-puv3.c:646: error: implicit declaration of
function 'pgprot_noncached'
Signed-off-by: Zhichuang Sun <sunzc522@gmail.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Joe Perches <joe@perches.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: linux-fbdev@vger.kernel.org
Acked-by: Xuetao Guan <gxt@mprc.pku.edu.cn>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1ff38c56cbd095c4c0dfa581a859ba3557830f78 upstream.
Need include "asm/pgtable.h" to include "asm-generic/pgtable-nopmd.h",
so can let 'pmd_t' defined. The related error with allmodconfig:
CC arch/unicore32/mm/alignment.o
In file included from arch/unicore32/mm/alignment.c:24:
arch/unicore32/include/asm/tlbflush.h:135: error: expected .). before .*. token
arch/unicore32/include/asm/tlbflush.h:154: error: expected .). before .*. token
In file included from arch/unicore32/mm/alignment.c:27:
arch/unicore32/mm/mm.h:15: error: expected .=., .,., .;., .sm. or ._attribute__. before .*. token
arch/unicore32/mm/mm.h:20: error: expected .=., .,., .;., .sm. or ._attribute__. before .*. token
arch/unicore32/mm/mm.h:25: error: expected .=., .,., .;., .sm. or ._attribute__. before .*. token
make[1]: *** [arch/unicore32/mm/alignment.o] Error 1
make: *** [arch/unicore32/mm] Error 2
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Acked-by: Xuetao Guan <gxt@mprc.pku.edu.cn>
Signed-off-by: Xuetao Guan <gxt@mprc.pku.edu.cn>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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DEBUG not defined
commit b7a7723513dc89f83d6df13206df55d4dc26e825 upstream.
This (widely used) construction:
if(printk_ratelimit())
dev_dbg()
Causes the ratelimiting to spam the kernel log with the "callbacks suppressed"
message below, even while the dev_dbg it is supposed to rate limit wouldn't
print anything because DEBUG is not defined for this device.
[ 533.803964] retire_playback_urb: 852 callbacks suppressed
[ 538.807930] retire_playback_urb: 852 callbacks suppressed
[ 543.811897] retire_playback_urb: 852 callbacks suppressed
[ 548.815745] retire_playback_urb: 852 callbacks suppressed
[ 553.819826] retire_playback_urb: 852 callbacks suppressed
So use dev_dbg_ratelimited() instead of this construction.
Signed-off-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit a5065eb6da55b226661456e6a7435f605df98111 upstream.
BugLink: http://bugs.launchpad.net/bugs/1305133
Malfunctioning or slow devices can cause a flood of dmesg SPAM.
I've ignored checkpatch.pl complaints about the use of printk_ratelimit() in favour
of prior art in sound/usb/pcm.c.
WARNING: Prefer printk_ratelimited or pr_<level>_ratelimited to printk_ratelimit
+ if (printk_ratelimit() &&
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Eldad Zack <eldad@fogrefinery.com>
Cc: Daniel Mack <zonque@gmail.com>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 6979f8d28049879e6147767d93ba6732c8bd94f4 upstream.
Commit c49436b657d0 (serial: 8250_dw: Improve unwritable LCR workaround)
caused a regression. It added a check that the LCR was written properly
to detect and workaround the busy quirk, but the behaviour of bit 5
(UART_LCR_SPAR) differs between IP versions 3.00a and 3.14c per the
docs. On older versions this caused the check to fail and it would
repeatedly force idle and rewrite the LCR register, causing delays and
preventing any input from serial being received.
This is fixed by masking out UART_LCR_SPAR before making the comparison.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Tim Kryger <tim.kryger@linaro.org>
Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: Matt Porter <matt.porter@linaro.org>
Cc: Markus Mayer <markus.mayer@linaro.org>
Tested-by: Tim Kryger <tim.kryger@linaro.org>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit c49436b657d0a56a6ad90d14a7c3041add7cf64d upstream.
When configured with UART_16550_COMPATIBLE=NO or in versions prior to
the introduction of this option, the Designware UART will ignore writes
to the LCR if the UART is busy. The current workaround saves a copy of
the last written LCR and re-writes it in the ISR for a special interrupt
that is raised when a write was ignored.
Unfortunately, interrupts are typically disabled prior to performing a
sequence of register writes that include the LCR so the point at which
the retry occurs is too late. An example is serial8250_do_set_termios()
where an ignored LCR write results in the baud divisor not being set and
instead a garbage character is sent out the transmitter.
Furthermore, since serial_port_out() offers no way to indicate failure,
a serious effort must be made to ensure that the LCR is actually updated
before returning back to the caller. This is difficult, however, as a
UART that was busy during the first attempt is likely to still be busy
when a subsequent attempt is made unless some extra action is taken.
This updated workaround reads back the LCR after each write to confirm
that the new value was accepted by the hardware. Should the hardware
ignore a write, the TX/RX FIFOs are cleared and the receive buffer read
before attempting to rewrite the LCR out of the hope that doing so will
force the UART into an idle state. While this may seem unnecessarily
aggressive, writes to the LCR are used to change the baud rate, parity,
stop bit, or data length so the data that may be lost is likely not
important. Admittedly, this is far from ideal but it seems to be the
best that can be done given the hardware limitations.
Lastly, the revised workaround doesn't touch the LCR in the ISR, so it
avoids the possibility of a "serial8250: too much work for irq" lock up.
This problem is rare in real situations but can be reproduced easily by
wiring up two UARTs and running the following commands.
# stty -F /dev/ttyS1 echo
# stty -F /dev/ttyS2 echo
# cat /dev/ttyS1 &
[1] 375
# echo asdf > /dev/ttyS1
asdf
[ 27.700000] serial8250: too much work for irq96
[ 27.700000] serial8250: too much work for irq96
[ 27.710000] serial8250: too much work for irq96
[ 27.710000] serial8250: too much work for irq96
[ 27.720000] serial8250: too much work for irq96
[ 27.720000] serial8250: too much work for irq96
[ 27.730000] serial8250: too much work for irq96
[ 27.730000] serial8250: too much work for irq96
[ 27.740000] serial8250: too much work for irq96
Signed-off-by: Tim Kryger <tim.kryger@linaro.org>
Reviewed-by: Matt Porter <matt.porter@linaro.org>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
[wangnan: backport to 3.10.43:
- adjust context
- remove unneeded local var]
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 33acbb82695f84e9429c1f7fbdeb4588dea12ffa upstream.
When a serial port is configured for RTS/CTS flow control, serial core
will disable the transmitter if it observes CTS is de-asserted. This is
perfectly reasonable and appropriate when the UART lacks the ability to
automatically perform CTS flow control.
However, if the UART hardware can manage flow control automatically, it
is important that software not get involved. When the DesignWare UART
enables 16C750 style auto-RTS/CTS it stops generating interrupts for
changes in CTS state so software mostly stays out of the way. However,
it does report the true state of CTS in the MSR so software may notice
it is de-asserted and respond by improperly disabling the transmitter.
Once this happens the transmitter will be blocked forever.
To avoid this situation, we simply lie to the 8250 and serial core by
reporting that CTS is asserted whenever auto-RTS/CTS mode is enabled.
Signed-off-by: Tim Kryger <tim.kryger@linaro.org>
Reviewed-by: Matt Porter <matt.porter@linaro.org>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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