The irqsoff and friends tracers help in finding causes of latency in the
kernel. The also work with the function tracer to show what was happening
when interrupts or preemption are disabled. But the function tracer has
a bit of an overhead and can cause exagerated readings.
Currently, when tracing with /proc/sys/kernel/ftrace_enabled = 0, where the
function tracer is disabled, the information that is provided can end up
being useless. For example, a 2 and a half millisecond latency only showed:
# tracer: preemptirqsoff
#
# preemptirqsoff latency trace v1.1.5 on 2.6.32
# --------------------------------------------------------------------
# latency: 2463 us, #4/4, CPU#2 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
# -----------------
# | task: -4242 (uid:0 nice:0 policy:0 rt_prio:0)
# -----------------
# => started at: _spin_lock_irqsave
# => ended at: remove_wait_queue
#
#
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| /_--=> lock-depth
# |||||/ delay
# cmd pid |||||| time | caller
# \ / |||||| \ | /
hackbenc-4242 2d.... 0us!: trace_hardirqs_off <-_spin_lock_irqsave
hackbenc-4242 2...1. 2463us+: _spin_unlock_irqrestore <-remove_wait_queue
hackbenc-4242 2...1. 2466us : trace_preempt_on <-remove_wait_queue
The above lets us know that hackbench with pid 2463 grabbed a spin lock
somewhere and enabled preemption at remove_wait_queue. This helps a little
but where this actually happened is not informative.
This patch adds the stack dump to the end of the irqsoff tracer. This provides
the following output:
hackbenc-4242 2d.... 0us!: trace_hardirqs_off <-_spin_lock_irqsave
hackbenc-4242 2...1. 2463us+: _spin_unlock_irqrestore <-remove_wait_queue
hackbenc-4242 2...1. 2466us : trace_preempt_on <-remove_wait_queue
hackbenc-4242 2...1. 2467us : <stack trace>
=> sub_preempt_count
=> _spin_unlock_irqrestore
=> remove_wait_queue
=> free_poll_entry
=> poll_freewait
=> do_sys_poll
=> sys_poll
=> system_call_fastpath
Now we see that the culprit of this latency was the free_poll_entry code.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
I've been asked a few times about how to find out what is calling
some location in the kernel. One way is to use dynamic function tracing
and implement the func_stack_trace. But this only finds out who is
calling a particular function. It does not tell you who is calling
that function and entering a specific if conditional.
I have myself implemented a quick version of trace_dump_stack() for
this purpose a few times, and just needed it now. This is when I realized
that this would be a good tool to have in the kernel like trace_printk().
Using trace_dump_stack() is similar to dump_stack() except that it
writes to the trace buffer instead and can be used in critical locations.
For example:
@@ -5485,8 +5485,12 @@ need_resched_nonpreemptible:
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
if (unlikely(signal_pending_state(prev->state, prev)))
prev->state = TASK_RUNNING;
- else
+ else {
deactivate_task(rq, prev, 1);
+ trace_printk("Deactivating task %s:%d\n",
+ prev->comm, prev->pid);
+ trace_dump_stack();
+ }
switch_count = &prev->nvcsw;
}
Produces:
<...>-3249 [001] 296.105269: schedule: Deactivating task ntpd:3249
<...>-3249 [001] 296.105270: <stack trace>
=> schedule
=> schedule_hrtimeout_range
=> poll_schedule_timeout
=> do_select
=> core_sys_select
=> sys_select
=> system_call_fastpath
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add nodes for PPC440SPe DMA, I2O, XOR engines and Memory
Queue module which are used in the updated PPC440SPe ADMA
driver. Also extend plb ranges property to specify address
ranges for DMA0/1 and I2O engines.
Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
This patch fixes 2 edge cases in using kgdb in conjunction with gdb.
1) kgdb_deactivate_sw_breakpoints() should process the entire array of
breakpoints. The failure to do so results in breakpoints that you
cannot remove, because a break point can only be removed if its
state flag is set to BP_SET.
The easy way to duplicate this problem is to plant a break point in
a kernel module and then unload the kernel module.
2) kgdb_activate_sw_breakpoints() should process the entire array of
breakpoints. The failure to do so results in missed breakpoints
when a breakpoint cannot be activated.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
On some architectures for the segv trap, gdb wants to pass the signal
back on continue. For kgdb this is not the default behavior, because
it can cause the kernel to crash if you arbitrarily pass back a
exception outside of kgdb.
Instead of causing instability, pass a message back to gdb about the
supported kgdb signal passing and execute a standard kgdb continue
operation.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
On an SMP system the kgdb_single_step flag has the possibility to
indefinitely hang the system in the case. Consider the case where,
CPU 1 has the schedule lock and CPU 0 is set to single step, there is
no way for CPU 0 to run another task.
The easy way to observe the problem is to make 2 cpus busy, and run
the kgdb test suite. You will see that it hangs the system very
quickly.
while [ 1 ] ; do find /proc > /dev/null 2>&1 ; done &
while [ 1 ] ; do find /proc > /dev/null 2>&1 ; done &
echo V1 > /sys/module/kgdbts/parameters/kgdbts
The side effect of this patch is that there is the possibility
to miss a breakpoint in the case that a single step operation
was executed to step over a breakpoint in common code.
The trade off of the missed breakpoint is preferred to
hanging the kernel. This can be fixed in the future by
using kprobes or another strategy to step over planted
breakpoints with out of line execution.
CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The kgdb core should not assume that a single step operation of a
kernel thread will complete on the same CPU. The single step flag is
set at the "thread" level and it is possible in a multi cpu system
that a kernel thread can get scheduled on another cpu the next time it
is run.
As a further safety net in case a slave cpu is hung, the debug master
cpu will try 100 times before giving up and assuming control of the
slave cpus is no longer possible. It is more useful to be able to get
some information out of kgdb instead of spinning forever.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
It is possible for the user_mode_vm(regs) check to return true on the
i368 arch for a non master kgdb cpu or when the master kgdb cpu
handles the NMI watch dog exception.
The solution is simply to select the correct gdb_ss location
based on the check to user_mode_vm(regs).
CC: Ingo Molnar <mingo@elte.hu>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Some versions of gcc replace calls to strstr() with single-character
"needle" string parameters by calls to strchr() behind our back.
This causes linking errors if strchr() is defined as an inline function
in <asm/string.h> (e.g. on m68k, which BTW doesn't have kgdb support).
Prevent this by explicitly calling strchr() instead.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Prevent write to put_buf[BUFMAX] in kgdb test suite.
If put_buf_cnt was BUFMAX - 1 at the earlier test,
`\0' is written to put_buf[BUFMAX].
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Roel Kluin reported an error found with Parfait. Where we want to
ensure that that kgdb_info[-1] never gets accessed.
Also check to ensure any negative tid does not exceed the size of the
shadow CPU array, else report critical debug context because it is an
internal kgdb failure.
Reported-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Move OPTi93x controls definitions to the opti93x driver
from the common wss-lib library module. These controls
are used only by the opti93x driver.
Also, fix capture source names. They are the same as
opl3sa2 names.
Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The als100 driver is so similar to the dt019x/als007 driver
that one driver's source can be used for both drivers with
only few changes. Merge the dt019x driver into the als100.
Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
For codecs without EPSS support (G45/IbexPeak), the hotplug event will
be lost if the HDA is powered off during the time. After that the pin
presence detection verb returns inaccurate info.
So always power-on HDA link for !EPSS codecs.
KarL offers the fact and Takashi recommends to flag hda_bus. Thanks!
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Add definitions of rmb() and cpu_relax() and include the ARM
unistd.h header. The __kuser_memory_barrier helper in the helper
page is used to provide the correct memory barrier depending on
the CPU type.
[ The rmb() will work on v6 and v7, segfault on v5. Dynamic
detection to add v5 support will be added later. ]
Signed-off-by: Jamie Iles <jamie.iles@picochip.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mikael Pettersson <mikpe@it.uu.se>
LKML-Reference: <1260534009-5394-1-git-send-email-jamie.iles@picochip.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The timer stop callback can be called from snd_timer_interrupt(), which
is called from the hrtimer callback. Since hrtimer_cancel() waits for
the callback completion, this eventually results in a lock-up.
This patch fixes the problem by just toggling a flag at stop callback
and call hrtimer_cancel() later.
Reported-and-tested-by: Wojtek Zabolotny <W.Zabolotny@elka.pw.edu.pl>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The comment in there used to be true, but these days do_brk() does
the arch-specific check that covers what we open-coded here. So we
can use sys_brk() just fine, only need to do force_successful_syscall_return()
after it.
See commit 3a45975681 - that's when the
checks in do_brk() had been originally added.
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We've had TASK_SIZE set to 1<<31 for 31bit tasks since May 2004.
Before that old32_mmap() had to deal with do_mmap_pgoff() giving
it an address out of range. It had tried to do that by checking
return value and doing do_munmap() (at wrong address, BTW).
IOW, that code had been dead for 5.5 years (and bogus - for 8).
Kill.
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... we should call mm ->get_unmapped_area() instead and let our caller
do the final checks.
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Take locating vma and checks on it to a separate helper (it will be
shared between MREMAP_FIXED/non-MREMAP_FIXED cases when we split
them in the next patch)
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This adds a drm/kms staging non-API stable driver for GPUs from NVIDIA.
This driver is a KMS-based driver and requires a compatible nouveau
userspace libdrm and nouveau X.org driver.
This driver requires firmware files not available in this kernel tree,
interested parties can find them via the nouveau project git archive.
This driver is reverse engineered, and is in no way supported by nVidia.
Support for nearly the complete range of nvidia hw from nv04->g80 (nv50)
is available, and the kms driver should support driving nearly all
output types (displayport is under development still) along with supporting
suspend/resume.
This work is all from the upstream nouveau project found at
nouveau.freedesktop.org.
The original authors list from nouveau git tree is:
Anssi Hannula <anssi.hannula@iki.fi>
Ben Skeggs <bskeggs@redhat.com>
Francisco Jerez <currojerez@riseup.net>
Maarten Maathuis <madman2003@gmail.com>
Marcin Kościelnicki <koriakin@0x04.net>
Matthew Garrett <mjg@redhat.com>
Matt Parnell <mparnell@gmail.com>
Patrice Mandin <patmandin@gmail.com>
Pekka Paalanen <pq@iki.fi>
Xavier Chantry <shiningxc@gmail.com>
along with project founder Stephane Marchesin <marchesin@icps.u-strasbg.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
For embedded platforms, we want to be able to build the perf
tools on a build machine to run on a different arch. This patch
allows $CROSS_COMPILE to set the cross compiler.
Additionally, if NO_LIBPERL is set, then don't use perl include
paths as they will be for the host arch.
Signed-off-by: Jamie Iles <jamie.iles@picochip.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1260523260-15694-2-git-send-email-jamie.iles@picochip.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The type got changed to u32, so %lx generated warnings
(and thus build failure on sparc64)
Stephen Rothwell fixed it like so:
- printk("clockevent: mult[%lx] shift[%d]\n",
+ printk("clockevent: mult[%ux] shift[%d]\n",
But that's not a valid transformation, we now get:
clockevent: mult[51539607x] shift[32]
in the logs.
Fix it to use the correct plain "%x" instead.
Signed-off-by: David S. Miller <davem@davemloft.net>
Extends the existing Samsung USB IrDA (0419:0001) quirk with newly reported 171
byte variant. It needs the same quirk as the other devices already supported
by hid-samsung (wrong logical range)
Refactors duplicate trace call into local helper function.
The original bug report for the new variant is available at the second half of
this ticket page:
https://bugs.launchpad.net/bugs/326986
Signed-off-by: Robert Schedel <r.schedel@yahoo.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Xiaotian Feng triggered a list corruption in the clock events list on
CPU hotplug and debugged the root cause.
If a CPU registers more than one per cpu clock event device, then only
the active clock event device is removed on CPU_DEAD. The unused
devices are kept in the clock events device list.
On CPU up the clock event devices are registered again, which means
that we list_add an already enqueued list_head. That results in list
corruption.
Resolve this by removing all devices which are associated to the dead
CPU on CPU_DEAD.
Reported-by: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Xiaotian Feng <dfeng@redhat.com>
Cc: stable@kernel.org
This mirrors commit 196f02bf90
(powerpc: perf_event: Add alignment-faults and emulation-faults software events)
Signed-off-by: David S. Miller <davem@davemloft.net>
Jens found the following crash/regression:
[ 0.000000] found SMP MP-table at [ffff8800000fdd80] fdd80
[ 0.000000] Kernel panic - not syncing: Overlapping early reservations 12-f011 MP-table mpc to 0-fff BIOS data page
and
[ 0.000000] Kernel panic - not syncing: Overlapping early reservations 12-f011 MP-table mpc to 6000-7fff TRAMPOLINE
and bisected it to b24c2a9 ("x86: Move find_smp_config()
earlier and avoid bootmem usage").
It turns out the BIOS is using the first 64k for mptable,
without reserving it.
So try to find good range for the real-mode trampoline instead of
hard coding it, in case some bios tries to use that range for sth.
Reported-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Tested-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <4B21630A.6000308@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
