Impact: prevent locking up by lockdep tracer
The lockdep tracer uses trace_vprintk and thus trace_vprintk can not
call back into lockdep without locking up.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Using the function_graph tracer in recent kernels generates a spew of
preemption BUGs. Fix this by not requiring trace_clock_local() users
to disable preemption themselves.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
There existed a lot of <space><tab>'s in the tracing code. This
patch removes them.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up / comments
The comments that described the ftrace macros to manipulate the
TRACE_EVENT and TRACE_FORMAT macros no longer match the code.
This patch updates them.
Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
In trying to stay consistant with the C style format in the TRACE_EVENT
macro, it makes more sense to do the printk after the assigning of
the variables.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The event directory files type and available_types were no longer
needed with the new TRACE_EVENT_FORMAT macros, they were deleted.
But by accident the available_events file was also removed.
This patch brings it back.
Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: micro-optimization
We can avoid the sched domain walk on try_to_wake_up() when we know
there are no groups.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1236603381.8389.455.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix to prevent crash on calling NULL function pointer
The ftrace internal records have their format exported via the event
system under the ftrace subsystem. These are only for exporting the
format to allow binary readers to be able to parse them in a binary
output.
The ftrace subsystem events can only be enabled via the ftrace tracers
and do not have a registering function. The event files expect the
event record to have registering function and will call it directly.
Passing in a ftrace subsystem event will cause the kernel to crash
because it will execute a NULL pointer.
This patch prevents the ftrace subsystem from being viewable to the
event enabling files.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
The offsetof and sizeof are of type size_t, and instead of typecasting
them to unsigned int for printk formatting, one could just use %zu.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: cleanup
Obviously, this goto is useless. Remove it.
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Roland McGrath <roland@redhat.com>
LKML-Reference: <20090310093447.GC3179@hack>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
"for (++cpu ; cpu < num_possible_cpus(); cpu++)" statement assumes
possible cpus have continuous number - but that's a wrong assumption.
Insted, cpumask_next() should be used.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20090310104437.A480.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
The TRACE_EVENT_FORMAT macro is no longer used by trace points
and only the DECLARE_TRACE, TRACE_FORMAT or TRACE_EVENT macros should
be used by them. Although the TRACE_EVENT_FORMAT macro is still used
by the internal tracing utility, it should not be used in core
kernel code.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up and enhancement
The TRACE_EVENT_FORMAT macro looks quite ugly and is limited in its
ability to save data as well as to print the record out. Working with
Ingo Molnar, we came up with a new format that is much more pleasing to
the eye of C developers. This new macro is more C style than the old
macro, and is more obvious to what it does.
Here's the example. The only updated macro in this patch is the
sched_switch trace point.
The old method looked like this:
TRACE_EVENT_FORMAT(sched_switch,
TP_PROTO(struct rq *rq, struct task_struct *prev,
struct task_struct *next),
TP_ARGS(rq, prev, next),
TP_FMT("task %s:%d ==> %s:%d",
prev->comm, prev->pid, next->comm, next->pid),
TRACE_STRUCT(
TRACE_FIELD(pid_t, prev_pid, prev->pid)
TRACE_FIELD(int, prev_prio, prev->prio)
TRACE_FIELD_SPECIAL(char next_comm[TASK_COMM_LEN],
next_comm,
TP_CMD(memcpy(TRACE_ENTRY->next_comm,
next->comm,
TASK_COMM_LEN)))
TRACE_FIELD(pid_t, next_pid, next->pid)
TRACE_FIELD(int, next_prio, next->prio)
),
TP_RAW_FMT("prev %d:%d ==> next %s:%d:%d")
);
The above method is hard to read and requires two format fields.
The new method:
/*
* Tracepoint for task switches, performed by the scheduler:
*
* (NOTE: the 'rq' argument is not used by generic trace events,
* but used by the latency tracer plugin. )
*/
TRACE_EVENT(sched_switch,
TP_PROTO(struct rq *rq, struct task_struct *prev,
struct task_struct *next),
TP_ARGS(rq, prev, next),
TP_STRUCT__entry(
__array( char, prev_comm, TASK_COMM_LEN )
__field( pid_t, prev_pid )
__field( int, prev_prio )
__array( char, next_comm, TASK_COMM_LEN )
__field( pid_t, next_pid )
__field( int, next_prio )
),
TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
__entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
__entry->next_comm, __entry->next_pid, __entry->next_prio),
TP_fast_assign(
memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
__entry->prev_pid = prev->pid;
__entry->prev_prio = prev->prio;
memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
__entry->next_pid = next->pid;
__entry->next_prio = next->prio;
)
);
This macro is called TRACE_EVENT, it is broken up into 5 parts:
TP_PROTO: the proto type of the trace point
TP_ARGS: the arguments of the trace point
TP_STRUCT_entry: the structure layout of the entry in the ring buffer
TP_printk: the printk format
TP_fast_assign: the method used to write the entry into the ring buffer
The structure is the definition of how the event will be saved in the
ring buffer. The printk is used by the internal tracing in case of
an oops, and the kernel needs to print out the format of the record
to the console. This the TP_printk gives a means to show the records
in a human readable format. It is also used to print out the data
from the trace file.
The TP_fast_assign is executed directly. It is basically like a C function,
where the __entry is the handle to the record.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
This removes the custom made STR(x) macros in the tracer and uses
the generic __stringify macro instead.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
The macros TPPROTO, TPARGS, TPFMT, TPRAWFMT, and TPCMD all look a bit
ugly. This patch adds an underscore to their names.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix compiler warnings
On x86_64 sizeof and offsetof are treated as long, where as on x86_32
they are int. This patch typecasts them to unsigned int to avoid
one arch giving warnings while the other does not.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
CLONE_PARENT can fool the ->self_exec_id/parent_exec_id logic. If we
re-use the old parent, we must also re-use ->parent_exec_id to make
sure exit_notify() sees the right ->xxx_exec_id's when the CLONE_PARENT'ed
task exits.
Also, move down the "p->parent_exec_id = p->self_exec_id" thing, to place
two different cases together.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Frans Pop reported the crash below when running an s390 kernel under Hercules:
Kernel BUG at 000738b4 verbose debug info unavailable!
fixpoint divide exception: 0009 #1! SMP
Modules linked in: nfs lockd nfs_acl sunrpc ctcm fsm tape_34xx
cu3088 tape ccwgroup tape_class ext3 jbd mbcache dm_mirror dm_log dm_snapshot
dm_mod dasd_eckd_mod dasd_mod
CPU: 0 Not tainted 2.6.27.19 #13
Process awk (pid: 2069, task: 0f9ed9b8, ksp: 0f4f7d18)
Krnl PSW : 070c1000 800738b4 (acct_update_integrals+0x4c/0x118)
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0
Krnl GPRS: 00000000 000007d0 7fffffff fffff830
00000000 ffffffff 00000002 0f9ed9b8
00000000 00008ca0 00000000 0f9ed9b8
0f9edda4 8007386e 0f4f7ec8 0f4f7e98
Krnl Code: 800738aa: a71807d0 lhi %r1,2000
800738ae: 8c200001 srdl %r2,1
800738b2: 1d21 dr %r2,%r1
>800738b4: 5810d10e l %r1,270(%r13)
800738b8: 1823 lr %r2,%r3
800738ba: 4130f060 la %r3,96(%r15)
800738be: 0de1 basr %r14,%r1
800738c0: 5800f060 l %r0,96(%r15)
Call Trace:
( <000000000004fdea>! blocking_notifier_call_chain+0x1e/0x2c)
<0000000000038502>! do_exit+0x106/0x7c0
<0000000000038c36>! do_group_exit+0x7a/0xb4
<0000000000038c8e>! SyS_exit_group+0x1e/0x30
<0000000000021c28>! sysc_do_restart+0x12/0x16
<0000000077e7e924>! 0x77e7e924
Reason for this is that cpu time accounting usually only happens from
interrupt context, but acct_update_integrals gets also called from
process context with interrupts enabled.
So in acct_update_integrals we may end up with the following scenario:
Between reading tsk->stime/tsk->utime and tsk->acct_timexpd an interrupt
happens which updates accouting values. This causes acct_timexpd to be
greater than the former stime + utime. The subsequent calculation of
dtime = cputime_sub(time, tsk->acct_timexpd);
will be negative and the division performed by
cputime_to_jiffies(dtime)
will generate an exception since the result won't fit into a 32 bit
register.
In order to fix this just always disable interrupts while accessing any
of the accounting values.
Reported by: Frans Pop <elendil@planet.nl>
Tested by: Frans Pop <elendil@planet.nl>
Cc: stable@kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: improve workqueue tracer output
Currently, /sys/kernel/debug/tracing/trace_stat/workqueues can display
wrong and strange thread names.
Why?
Currently, ftrace has tracing_record_cmdline()/trace_find_cmdline()
convenience function that implements a task->comm string cache.
This can avoid unnecessary memcpy overhead and the workqueue tracer
uses it.
However, in general, any trace statistics feature shouldn't use
tracing_record_cmdline() because trace statistics can display
very old process. Then comm cache can return wrong string because
recent process overrides the cache.
Fortunately, workqueue trace guarantees that displayed processes
are live. Thus we can search comm string from PID at display time.
<before>
% cat workqueues
# CPU INSERTED EXECUTED NAME
# | | | |
7 431913 431913 kondemand/7
7 0 0 tail
7 21 21 git
7 0 0 ls
7 9 9 cat
7 832632 832632 unix_chkpwd
7 236292 236292 ls
Note: tail, git, ls, cat unix_chkpwd are obiously not workqueue thread.
<after>
% cat workqueues
# CPU INSERTED EXECUTED NAME
# | | | |
7 510 510 kondemand/7
7 0 0 kmpathd/7
7 15 15 ata/7
7 0 0 aio/7
7 11 11 kblockd/7
7 1063 1063 work_on_cpu/7
7 167 167 events/7
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Remove a few leftovers and clean up the code a bit.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: faster and lighter tracing
Now that we have trace_bprintk() which is faster and consume lesser
memory than trace_printk() and has the same purpose, we can now drop
the old implementation in favour of the binary one from trace_bprintk(),
which means we move all the implementation of trace_bprintk() to
trace_printk(), so the Api doesn't change except that we must now use
trace_seq_bprintk() to print the TRACE_PRINT entries.
Some changes result of this:
- Previously, trace_bprintk depended of a single tracer and couldn't
work without. This tracer has been dropped and the whole implementation
of trace_printk() (like the module formats management) is now integrated
in the tracing core (comes with CONFIG_TRACING), though we keep the file
trace_printk (previously trace_bprintk.c) where we can find the module
management. Thus we don't overflow trace.c
- changes some parts to use trace_seq_bprintk() to print TRACE_PRINT entries.
- change a bit trace_printk/trace_vprintk macros to support non-builtin formats
constants, and fix 'const' qualifiers warnings. But this is all transparent for
developers.
- etc...
V2:
- Rebase against last changes
- Fix mispell on the changelog
V3:
- Rebase against last changes (moving trace_printk() to kernel.h)
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add a generic printk() for tracing, like trace_printk()
trace_bprintk() uses the infrastructure to record events on ring_buffer.
[ fweisbec@gmail.com: ported to latest -tip, made it work if
!CONFIG_MODULES, never free the format strings from modules
because we can't keep track of them and conditionnaly create
the ftrace format strings section (reported by Steven Rostedt) ]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: save on memory for tracing
Current tracers are typically using a struct(like struct ftrace_entry,
struct ctx_switch_entry, struct special_entr etc...)to record a binary
event. These structs can only record a their own kind of events.
A new kind of tracer need a new struct and a lot of code too handle it.
So we need a generic binary record for events. This infrastructure
is for this purpose.
[fweisbec@gmail.com: rebase against latest -tip, make it safe while sched
tracing as reported by Steven Rostedt]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use the mutual exclusion provided by the text edit lock in the kprobes code. It
allows coherent manipulation of the kernel code by other subsystems.
Changelog:
Move the kernel_text_lock/unlock out of the for loops.
Use text_mutex directly instead of a function.
Remove whitespace modifications.
(note : kprobes_mutex is always taken outside of text_mutex)
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <49B14306.2080202@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Use test_tsk_need_resched(), set_tsk_need_resched(), need_resched()
instead of using TIF_NEED_RESCHED.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <49B10BA4.9070209@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix deadlock while using set_ftrace_pid
Reproducer:
# cd /sys/kernel/debug/tracing
# echo $$ > set_ftrace_pid
then, console becomes hung.
Details:
when writing set_ftracepid, kernel callstack is following
ftrace_pid_write()
mutex_lock(&ftrace_lock);
ftrace_update_pid_func()
mutex_lock(&ftrace_lock);
mutex_unlock(&ftrace_lock);
mutex_unlock(&ftrace_lock);
then, system always deadlocks when ftrace_pid_write() is called.
In past days, ftrace_pid_write() used ftrace_start_lock, but
commit e6ea44e9b4 consolidated
ftrace_start_lock to ftrace_lock.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <20090306151155.0778.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add reserved allocation functionality and use it for module
percpu variables
This patch implements reserved allocation from the first chunk. When
setting up the first chunk, arch can ask to set aside certain number
of bytes right after the core static area which is available only
through a separate reserved allocator. This will be used primarily
for module static percpu variables on architectures with limited
relocation range to ensure that the module perpcu symbols are inside
the relocatable range.
If reserved area is requested, the first chunk becomes reserved and
isn't available for regular allocation. If the first chunk also
includes piggy-back dynamic allocation area, a separate chunk mapping
the same region is created to serve dynamic allocation. The first one
is called static first chunk and the second dynamic first chunk.
Although they share the page map, their different area map
initializations guarantee they serve disjoint areas according to their
purposes.
If arch doesn't setup reserved area, reserved allocation is handled
like any other allocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Impact: allow user apps to read binary format of basic ftrace entries
Currently, only defined raw events export their formats so a binary
reader can parse them. There's no reason that the default ftrace entries
can't export their formats.
This patch adds a subsystem called "ftrace" in the events directory
that includes the ftrace entries for basic ftrace recorded items.
These only have three files in the events directory:
type : printf
available_types : printf
format : format for the event entry
For example:
# cat /debug/tracing/events/ftrace/wakeup/format
name: wakeup
ID: 3
format:
field:unsigned char type; offset:0; size:1;
field:unsigned char flags; offset:1; size:1;
field:unsigned char preempt_count; offset:2; size:1;
field:int pid; offset:4; size:4;
field:int tgid; offset:8; size:4;
field:unsigned int prev_pid; offset:12; size:4;
field:unsigned char prev_prio; offset:16; size:1;
field:unsigned char prev_state; offset:17; size:1;
field:unsigned int next_pid; offset:20; size:4;
field:unsigned char next_prio; offset:24; size:1;
field:unsigned char next_state; offset:25; size:1;
field:unsigned int next_cpu; offset:28; size:4;
print fmt: "%u:%u:%u ==+ %u:%u:%u [%03u]"
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
Move the macro that creates the event format file to a separate header.
This will allow the default ftrace events to use this same macro
to create the formats to read those events.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: cleanup
All file_operations structures should be constant. No one is going to
change them.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Clean up menu structure, introduce TRACING_SUPPORT switch that signals
whether an architecture supports various instrumentation mechanisms.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix function graph trace hang / drop pointless softirq on UP
While debugging a function graph trace hang on an old PII, I saw
that it consumed most of its time on the timer interrupt. And
the domain rebalancing softirq was the most concerned.
The timer interrupt calls trigger_load_balance() which will
decide if it is worth to schedule a rebalancing softirq.
In case of builtin UP kernel, no problem arises because there is
no domain question.
In case of builtin SMP kernel running on an SMP box, still no
problem, the softirq will be raised each time we reach the
next_balance time.
In case of builtin SMP kernel running on a UP box (most distros
provide default SMP kernels, whatever the box you have), then
the CPU is attached to the NULL sched domain. So a kind of
unexpected behaviour happen:
trigger_load_balance() -> raises the rebalancing softirq later
on softirq: run_rebalance_domains() -> rebalance_domains() where
the for_each_domain(cpu, sd) is not taken because of the NULL
domain we are attached at. Which means rq->next_balance is never
updated. So on the next timer tick, we will enter
trigger_load_balance() which will always reschedule() the
rebalacing softirq:
if (time_after_eq(jiffies, rq->next_balance))
raise_softirq(SCHED_SOFTIRQ);
So for each tick, we process this pointless softirq.
This patch fixes it by checking if we are attached to the null
domain before raising the softirq, another possible fix would be
to set the maximal possible JIFFIES value to rq->next_balance if
we are attached to the NULL domain.
v2: build fix on UP
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <49af242d.1c07d00a.32d5.ffffc019@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: decrease hangs risks with the graph tracer on slow systems
Since the function graph tracer can spend too much time on timer
interrupts, it's better now to use the more lightweight local
clock. Anyway, the function graph traces are more reliable on a
per cpu trace.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <49af243d.06e9300a.53ad.ffff840c@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
The atomic debug modifiers are already defined in
kernel/lockdep_internals.h.
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <alpine.DEB.2.00.0903050222160.30401@chino.kir.corp.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Use a more generic name - this also allows the prototype to move
to kernel.h and be generally available to kernel developers who
want to do some quick tracing.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The latency tracers (irqsoff, preemptoff, preemptirqsoff, and wakeup)
are pretty useless with the default output format. This patch makes them
automatically enable the latency format when they are selected. They
also record the state of the latency option, and if it was not enabled
when selected, they disable it on reset.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
Both print_lat_fmt and print_trace_fmt do pretty much the same thing
except for one different function call. This patch consolidates the
two functions and adds an if statement to perform the difference.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
The trace and latency_trace function pointers are identical for
every tracer but the function tracer. The differences in the function
tracer are trivial (latency output puts paranthesis around parent).
This patch removes the latency_trace pointer and all prints will
now just use the trace output function pointer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
With the removal of the latency_trace file, we lost the ability
to see some of the finer details in a trace. Like the state of
interrupts enabled, the preempt count, need resched, and if we
are in an interrupt handler, softirq handler or not.
This patch simply creates an option to bring back the old format.
This also removes the warning about an unused variable that held
the latency_trace file operations.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The buffer used by trace_seq was updated incorrectly. Instead
of consuming what was actually read, it consumed the rest of the
buffer on reads.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix trace read to conform to standards
Andrew Morton, Theodore Tso and H. Peter Anvin brought to my attention
that a userspace read should not return -EFAULT if it succeeded in
copying anything. It should only return -EFAULT if it failed to copy
at all.
This patch modifies the check of copy_from_user and updates the return
code appropriately.
I also used H. Peter Anvin's short cut rule to just test ret == count.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
If a partial ring_buffer_page_read happens, then some of the
incremental timestamps may be lost. This patch writes the
recent timestamp into the page that is passed back to the caller.
A partial ring_buffer_page_read is where the full page would not
be written back to the user, and instead, just part of the page
is copied to the user. A full page would be a page swap with the
ring buffer and the timestamps would be correct.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix to ftrace_dump output corruption
The commit: b04cc6b1f6
tracing/core: introduce per cpu tracing files
added a new field to the iterator called cpu_file. This was a handle
to differentiate between the per cpu trace output files and the
all cpu "trace" file. The all cpu "trace" file required setting this
to TRACE_PIPE_ALL_CPU.
The problem is that the ftrace_dump sets up its own iterator but was
not updated to handle this change. The result was only CPU 0 printing
out on crash and a lot of "<0>"'s also being printed.
Reported-by: Thomas Gleixner <tglx@linuxtronix.de>
Tested-by: Darren Hart <dvhtc@us.ibm.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
If a machine is flooded by network frames, a cpu can loop
100% of its time inside ksoftirqd() without calling schedule().
This can delay RCU grace period to insane values.
Adding rcu_qsctr_inc() call in ksoftirqd() solves this problem.
Paul: "This regression was a result of the recent change from
"schedule()" to "cond_resched()", which got rid of that quiescent
state in the common case where a reschedule is not needed".
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clarify lockdep printk text
print_irq_inversion_bug() gets handed state strings of the form
"HARDIRQ", "SOFTIRQ", "RECLAIM_FS"
and appends "-irq-{un,}safe" to them, which is either redudant for *IRQ or
confusing in the RECLAIM_FS case.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1236175192.5330.7585.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In the recent mark_lock_irq() rework a bug snuck in that would report the
state of write locks causing irq inversion under a read lock as a read
lock.
Fix this by masking the read bit of the state when validating write
dependencies.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1236172646.5330.7450.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new feature
This patch creates a directory of files that correspond to the
per CPU ring buffers. These are binary files and are made to
be used with splice. This is the fastest way to extract data from
the ftrace ring buffers.
Thanks to Jiaying Zhang for pushing me to get this code fixed,
and to Eduard - Gabriel Munteanu for his splice code that helped
me debug my code.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Steven Rostedt