linux-toradex.git/include/linux, branch v3.3.3

serial/8250_pci: add a "force background timer" flag and use it for the "kt" serial port

2012-04-22T22:38:57+00:00

commit bc02d15a3452fdf9276e8fb89c5e504a88df888a upstream.

Workaround dropped notifications in the iir register.  Register reads
coincident with new interrupt notifications sometimes result in this
device clearing the interrupt event without reporting it in the read
data.

The serial core already has a heuristic for determining when a device
has an untrustworthy iir register.  In this case when we apriori know
that the iir is faulty use a flag (UPF_BUG_THRE) to bypass the test and
force usage of the background timer.

Acked-by: Alan Cox 
Reported-by: Nhan H Mai 
Reported-by: Sudhakar Mamillapalli 
Tested-by: Nhan H Mai 
Tested-by: Sudhakar Mamillapalli 
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

Revert "serial/8250_pci: setup-quirk workaround for the kt serial controller"

2012-04-22T22:38:57+00:00

commit 49b532f96fda23663f8be35593d1c1372c0f91e0 upstream.

This reverts commit 448ac154c957c4580531fa0c8f2045816fe2f0e7.

The semantic of UPF_IIR_ONCE is only guaranteed to workaround the race
condition in the kt serial's iir register if the only source of
interrupts is THRE (fifo-empty) events.  An modem status event at the
wrong time can again cause an iir read to drop the 'empty' status
leading to a hang.  So, revert this in preparation for using the
existing "I don't trust my iir register" workaround in the 8250 core
(UART_BUG_THRE).

Acked-by: Alan Cox 
Cc: Sudhakar Mamillapalli 
Reported-by: Nhan H Mai 
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

sched/x86: Fix overflow in cyc2ns_offset

2012-04-13T16:13:56+00:00

commit 9993bc635d01a6ee7f6b833b4ee65ce7c06350b1 upstream.

When a machine boots up, the TSC generally gets reset.  However,
when kexec is used to boot into a kernel, the TSC value would be
carried over from the previous kernel.  The computation of
cycns_offset in set_cyc2ns_scale is prone to an overflow, if the
machine has been up more than 208 days prior to the kexec.  The
overflow happens when we multiply *scale, even though there is
enough room to store the final answer.

We fix this issue by decomposing tsc_now into the quotient and
remainder of division by CYC2NS_SCALE_FACTOR and then performing
the multiplication separately on the two components.

Refactor code to share the calculation with the previous
fix in __cycles_2_ns().

Signed-off-by: Salman Qazi 
Acked-by: John Stultz 
Acked-by: Peter Zijlstra 
Cc: Paul Turner 
Cc: john stultz 
Link: http://lkml.kernel.org/r/20120310004027.19291.88460.stgit@dungbeetle.mtv.corp.google.com
Signed-off-by: Ingo Molnar 
Cc: Mike Galbraith 
Signed-off-by: Greg Kroah-Hartman

CIFS: Fix VFS lock usage for oplocked files

2012-04-13T16:13:54+00:00

commit 66189be74ff5f9f3fd6444315b85be210d07cef2 upstream.

We can deadlock if we have a write oplock and two processes
use the same file handle. In this case the first process can't
unlock its lock if the second process blocked on the lock in the
same time.

Fix it by using posix_lock_file rather than posix_lock_file_wait
under cinode->lock_mutex. If we request a blocking lock and
posix_lock_file indicates that there is another lock that prevents
us, wait untill that lock is released and restart our call.

Acked-by: Jeff Layton 
Signed-off-by: Pavel Shilovsky 
Signed-off-by: Steve French 
Signed-off-by: Greg Kroah-Hartman

x86,kgdb: Fix DEBUG_RODATA limitation using text_poke()

2012-04-13T16:13:54+00:00

commit 3751d3e85cf693e10e2c47c03c8caa65e171099b upstream.

There has long been a limitation using software breakpoints with a
kernel compiled with CONFIG_DEBUG_RODATA going back to 2.6.26. For
this particular patch, it will apply cleanly and has been tested all
the way back to 2.6.36.

The kprobes code uses the text_poke() function which accommodates
writing a breakpoint into a read-only page.  The x86 kgdb code can
solve the problem similarly by overriding the default breakpoint
set/remove routines and using text_poke() directly.

The x86 kgdb code will first attempt to use the traditional
probe_kernel_write(), and next try using a the text_poke() function.
The break point install method is tracked such that the correct break
point removal routine will get called later on.

Cc: x86@kernel.org
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: H. Peter Anvin 
Inspried-by: Masami Hiramatsu 
Signed-off-by: Jason Wessel 
Signed-off-by: Greg Kroah-Hartman

kgdb,debug_core: pass the breakpoint struct instead of address and memory

2012-04-13T16:13:54+00:00

commit 98b54aa1a2241b59372468bd1e9c2d207bdba54b upstream.

There is extra state information that needs to be exposed in the
kgdb_bpt structure for tracking how a breakpoint was installed.  The
debug_core only uses the the probe_kernel_write() to install
breakpoints, but this is not enough for all the archs.  Some arch such
as x86 need to use text_poke() in order to install a breakpoint into a
read only page.

Passing the kgdb_bpt structure to kgdb_arch_set_breakpoint() and
kgdb_arch_remove_breakpoint() allows other archs to set the type
variable which indicates how the breakpoint was installed.

Signed-off-by: Jason Wessel 
Signed-off-by: Greg Kroah-Hartman

PM / Sleep: Mitigate race between the freezer and request_firmware()

2012-04-13T16:13:54+00:00

commit 247bc03742545fec2f79939a3b9f738392a0f7b4 upstream.

There is a race condition between the freezer and request_firmware()
such that if request_firmware() is run on one CPU and
freeze_processes() is run on another CPU and usermodehelper_disable()
called by it succeeds to grab umhelper_sem for writing before
usermodehelper_read_trylock() called from request_firmware()
acquires it for reading, the request_firmware() will fail and
trigger a WARN_ON() complaining that it was called at a wrong time.
However, in fact, it wasn't called at a wrong time and
freeze_processes() simply happened to be executed simultaneously.

To avoid this race, at least in some cases, modify
usermodehelper_read_trylock() so that it doesn't fail if the
freezing of tasks has just started and hasn't been completed yet.
Instead, during the freezing of tasks, it will try to freeze the
task that has called it so that it can wait until user space is
thawed without triggering the scary warning.

For this purpose, change usermodehelper_disabled so that it can
take three different values, UMH_ENABLED (0), UMH_FREEZING and
UMH_DISABLED.  The first one means that usermode helpers are
enabled, the last one means "hard disable" (i.e. the system is not
ready for usermode helpers to be used) and the second one
is reserved for the freezer.  Namely, when freeze_processes() is
started, it sets usermodehelper_disabled to UMH_FREEZING which
tells usermodehelper_read_trylock() that it shouldn't fail just
yet and should call try_to_freeze() if woken up and cannot
return immediately.  This way all freezable tasks that happen
to call request_firmware() right before freeze_processes() is
started and lose the race for umhelper_sem with it will be
frozen and will sleep until thaw_processes() unsets
usermodehelper_disabled.  [For the non-freezable callers of
request_firmware() the race for umhelper_sem against
freeze_processes() is unfortunately unavoidable.]

Reported-by: Stephen Boyd 
Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

firmware_class: Do not warn that system is not ready from async loads

2012-04-13T16:13:53+00:00

commit 9b78c1da60b3c62ccdd1509f0902ad19ceaf776b upstream.

If firmware is requested asynchronously, by calling
request_firmware_nowait(), there is no reason to fail the request
(and warn the user) when the system is (presumably temporarily)
unready to handle it (because user space is not available yet or
frozen).  For this reason, introduce an alternative routine for
read-locking umhelper_sem, usermodehelper_read_lock_wait(), that
will wait for usermodehelper_disabled to be unset (possibly with
a timeout) and make request_firmware_work_func() use it instead of
usermodehelper_read_trylock().

Accordingly, modify request_firmware() so that it uses
usermodehelper_read_trylock() to acquire umhelper_sem and remove
the code related to that lock from _request_firmware().

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

firmware_class: Rework usermodehelper check

2012-04-13T16:13:53+00:00

commit fe2e39d8782d885755139304d8dba0b3e5bfa878 upstream.

Instead of two functions, read_lock_usermodehelper() and
usermodehelper_is_disabled(), used in combination, introduce
usermodehelper_read_trylock() that will only return with umhelper_sem
held if usermodehelper_disabled is unset (and will return -EAGAIN
otherwise) and make _request_firmware() use it.

Rename read_unlock_usermodehelper() to
usermodehelper_read_unlock() to follow the naming convention of the
new function.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

rtc: Provide flag for rtc devices that don't support UIE

2012-04-02T17:32:23+00:00

commit 4a649903f91232d02284d53724b0a45728111767 upstream.

Richard Weinberger noticed that on some RTC hardware that
doesn't support UIE mode, due to coarse granular alarms
(like 1minute resolution), the current virtualized RTC
support doesn't properly error out when UIE is enabled.

Instead the current code queues an alarm for the next second,
but it won't fire until up to a miniute later.

This patch provides a generic way to flag this sort of hardware
and fixes the issue on the mpc5121 where Richard noticed the
problem.

Reported-by: Richard Weinberger 
Tested-by: Richard Weinberger 
Signed-off-by: John Stultz 
Signed-off-by: Greg Kroah-Hartman