- 21 4月, 2017 22 次提交
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由 Steven Rostedt (VMware) 提交于
Have the traceon/off function probe triggers affect only the instance they are set in. This required making the trace_on/off accessible for other files in the tracing directory. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Modify the snapshot probe trigger to work with instances. This way the snapshot function trigger will only affect the instance that it is added to in the set_ftrace_filter file. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Pass around the local trace_array that is the descriptor for tracing instances, when enabling and disabling probes. This by default sets the enable/disable of event probe triggers to work with instances. The other probes will need some more work to get them working with instances. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
With the redesign of the registration and execution of the function probes (triggers), data can now be passed from the setup of the probe to the probe callers that are specific to the trace_array it is on. Although, all probes still only affect the toplevel trace array, this change will allow for instances to have their own probes separated from other instances and the top array. That is, something like the stacktrace probe can be set to trace only in an instance and not the toplevel trace array. This isn't implement yet, but this change sets the ground work for the change. When a probe callback is triggered (someone writes the probe format into set_ftrace_filter), it calls register_ftrace_function_probe() passing in init_data that will be used to initialize the probe. Then for every matching function, register_ftrace_function_probe() will call the probe_ops->init() function with the init data that was passed to it, as well as an address to a place holder that is associated with the probe and the instance. The first occurrence will have a NULL in the pointer. The init() function will then initialize it. If other probes are added, or more functions are part of the probe, the place holder will be passed to the init() function with the place holder data that it was initialized to the last time. Then this place_holder is passed to each of the other probe_ops functions, where it can be used in the function callback. When the probe_ops free() function is called, it can be called either with the rip of the function that is being removed from the probe, or zero, indicating that there are no more functions attached to the probe, and the place holder is about to be freed. This gives the probe_ops a way to free the data it assigned to the place holder if it was allocade during the first init call. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
In order to eventually have each trace_array instance have its own unique set of function probes (triggers), the trace array needs to hold the ops and the filters for the probes. This is the first step to accomplish this. Instead of having the private data of the probe ops point to the trace_array, create a separate list that the trace_array holds. There's only one private_data for a probe, we need one per trace_array. The probe ftrace_ops will be dynamically created for each instance, instead of being static. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Pass the trace_array associated to a ftrace_probe_ops into the probe_ops func(), init() and free() functions. The trace_array is the descriptor that describes a tracing instance. This will help create the infrastructure that will allow having function probes unique to tracing instances. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Add a link list to the trace_array to hold func probes that are registered. Currently, all function probes are the same for all instances as it was before, that is, only the top level trace_array holds the function probes. But this lays the ground work to have function probes be attached to individual instances, and having the event trigger only affect events in the given instance. But that work is still to be done. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
If the ftrace_hash_move_and_update_ops() fails, and an ops->free() function exists, then it needs to be called on all the ops that were added by this registration. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Now that the function probes have their own ftrace_ops, there's no reason to continue using the ftrace_func_hash to find which probe to call in the function callback. The ops that is passed in to the function callback is part of the probe_ops to call. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Have the function probes have their own ftrace_ops, and remove the trace_probe_ops. This simplifies some of the ftrace infrastructure code. Individual entries for each function is still allocated for the use of the output for set_ftrace_filter, but they will be removed soon too. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Currently unregister_ftrace_function_probe_func() is a void function. It does not give any feedback if an error occurred or no item was found to remove and nothing was done. Change it to return status and success if it removed something. Also update the callers to return that feedback to the user. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
The processes of updating a ops filter_hash is a bit complex, and requires setting up an old hash to perform the update. This is done exactly the same in two locations for the same reasons. Create a helper function that does it in one place. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
No users of the function probes uses the data field anymore. Remove it, and change the init function to take a void *data parameter instead of a void **data, because the init will just get the data that the registering function was received, and there's no state after it is called. The other functions for ftrace_probe_ops still take the data parameter, but it will currently only be passed NULL. It will stay as a parameter for future data to be passed to these functions. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
None of the probe users uses the data field anymore of the entry. They all have their own print() function. Remove showing the data field in the generic function as the data field will be going away. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
There are no users of unregister_ftrace_function_probe_all(). The only probe function that is used is unregister_ftrace_function_probe_func(). Rename the internal static function __unregister_ftrace_function_probe() to unregister_ftrace_function_probe_func() and make it global. Also remove the PROBE_TEST_FUNC as it would be always set. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Nothing calls unregister_ftrace_function_probe(). Remove it as well as the flag PROBE_TEST_DATA, as this function was the only one to set it. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
As the data pointer for individual ips will soon be removed and no longer passed to the callback function probe handlers, convert the rest of the function trigger counters over to the new ftrace_func_mapper helper functions. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
As the data pointer for individual ips will soon be removed and no longer passed to the callback function probe handlers, convert the snapshot trigger counter over to the new ftrace_func_mapper helper functions. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
In order to move the ops to the function probes directly, they need a way to map function ips to their own data without depending on the infrastructure of the function probes, as the data field will be going away. New helper functions are added that are based on the ftrace_hash code. ftrace_func_mapper functions are there to let the probes map ips to their data. These can be allocated by the probe ops, and referenced in the function callbacks. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
In preparation to cleaning up the probe function registration code, the "data" parameter will eventually be removed from the probe->func() call. Instead it will receive its own "ops" function, in which it can set up its own data that it needs to map. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Nothing uses "flags" in the ftrace_func_probe descriptor. Remove it. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
As nothing outside the tracing directory uses the function command mechanism, I'm moving the prototypes out of the include/linux/ftrace.h and into the local kernel/trace/trace.h header. I plan on making them hook to the trace_array structure which is local to kernel/trace, and I do not want to expose it to the rest of the kernel. This requires that the command functions must also be local to tracing. But luckily nothing else uses them. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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- 19 4月, 2017 5 次提交
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由 Steven Rostedt (VMware) 提交于
As nothing outside the tracing directory uses the function probes mechanism, I'm moving the prototypes out of the include/linux/ftrace.h and into the local kernel/trace/trace.h header. I plan on making them hook to the trace_array structure which is local to kernel/trace, and I do not want to expose it to the rest of the kernel. This requires that the probe functions must also be local to tracing. But luckily nothing else uses them. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
The set_ftrace_file lists both functions that are filtered, as well as function probes (triggers) that are attached to a function, like traceon or stacktrace, etc. The reading of this file is not as trivial as most pseudo files are, and there's been various bugs that have appeared in the past when there's a mix of probes and functions listed. There's also a difference when reading the file using dd with a block size of 1. This test performs the following: o Resets set_ftrace_filter o Makes sure only "#### all functions enabled ####" is listed (All checks uses cat, and dd with bs=1 and bs=100) o Adds a traceon trigger to schedule o Checks if only "#### all function enabled ####" and the trigger is there. o Adds tracing of schedule o Checks if only schedule and the trigger is there o Adds tracing of do_IRQ as well o Checks if only schedule, do_IRQ and the trigger is there o Adds a traceon trigger to do_IRQ o Checks if only schedule, do_IRQ and both triggers are there o Removes tracing of do_IRQ o Checks if only schedule and both triggers are there o Removes tracing of schedule o Checks if only "#### all functions enabled ####" and both triggers are there o Removes the triggers o Checks if only "#### all functions enabled ####" is there o Adds tracing of schedule o Checks if only schedule is there o Adds tracing of do_IRQ o Checks if only schedule and do_IRQ are there Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
This adds a test to test the function tiggers traceon and traceoff to make sure that it starts and stops tracing when a function is hit. The test performs the following: o Enables all events o Writes schedule:traceoff into set_ftrace_filter o Makes sure the tigger exists in the file o Makes sure the trace file no longer grows o Makes sure that tracing_on is now zero o Clears the trace file o Makes sure it's still empty o Removes the trigger o Makes sure tracing is still off (tracing_on is zero) o Writes schedule:traceon into set_ftrace_filter o Makes sure the trace file is no longer empty o Makes sure that tracing_on file is set to one o Removes the trigger o Makes sure the trigger is no longer there o Writes schedule:traceoff:3 into set_ftrace_filter o Makes sure that tracing_on turns off . Writes 1 into tracing_on . Makes sure that it turns off 2 more times o Writes 1 into tracing_on o Makes sure that tracing_on is still a one Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
This adds a test to enable and disable trace events via the function triggers. It tests enabling and disabling the sched:sched_switch event via the the event_enable and event_disable function triggers attached to the schedule() kernel function. The test does the following: o disable all events o disables or enables the sched_switch event o writes schedule:event_enable/disable:sched:sched_switch into set_ftrace_filter o 5 times it checks to make sure: . Writes 0/1 into the sched_switch/enable . Checks that the sched_switch/enable goes back to 1/0 o Resets the events o writes schedule:event_enable/disable:sched:sched_switch:3 into set_ftrace_filter o Does a loop of 3 to see that sched_switch/enable file gets updated o Makes sure the sched_switch/enable stops getting updated Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Just writing into the set_ftrace_filter file does not reset triggers, even though it can reset the function list. Triggers require writing the trigger name with a "!" prepended. It's worse that it requires the number if the trigger has a count associated to it. Add a reset_ftrace_filter function to the ftrace self tests to allow for the tests to have a generic way to clear them. It also resets any functions that are listed in that file as well. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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- 18 4月, 2017 3 次提交
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由 Namhyung Kim 提交于
In my virtual machine setup, running ftracetest failed on creating LOG_DIR on a read-only filesystem. It'd be convenient to provide an option to specify a different directory as log directory. Link: http://lkml.kernel.org/r/20170417024430.21194-4-namhyung@kernel.org Cc: Ingo Molnar <mingo@kernel.org> Acked-by: NMasami Hiramatsu <mhiramat@kernel.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Signed-off-by: NNamhyung Kim <namhyung@kernel.org> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Namhyung Kim 提交于
The function-fork option is same as event-fork that it tracks task fork/exit and set the pid filter properly. This can be useful if user wants to trace selected tasks including their children only. Link: http://lkml.kernel.org/r/20170417024430.21194-3-namhyung@kernel.orgSigned-off-by: NNamhyung Kim <namhyung@kernel.org> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
The trace_event benchmark thread runs in kernel space in an infinite loop while also calling cond_resched() in case anything else wants to schedule in. Unfortunately, on a PREEMPT kernel, that makes it a nop, in which case, this will never voluntarily schedule. That will cause synchronize_rcu_tasks() to forever block on this thread, while it is running. This is exactly what cond_resched_rcu_qs() is for. Use that instead. Acked-by: N"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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- 17 4月, 2017 1 次提交
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由 Steven Rostedt (VMware) 提交于
t_hash_start() does not increment *pos, where as t_next() must. But when t_next() does increment *pos, it must still pass in the original *pos to t_hash_start() otherwise it will skip the first instance: # cd /sys/kernel/debug/tracing # echo schedule:traceoff > set_ftrace_filter # echo do_IRQ:traceoff > set_ftrace_filter # echo call_rcu > set_ftrace_filter # cat set_ftrace_filter call_rcu schedule:traceoff:unlimited do_IRQ:traceoff:unlimited The above called t_hash_start() from t_start() as there was only one function (call_rcu), but if we add another function: # echo xfrm_policy_destroy_rcu >> set_ftrace_filter # cat set_ftrace_filter call_rcu xfrm_policy_destroy_rcu do_IRQ:traceoff:unlimited The "schedule:traceoff" disappears. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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- 16 4月, 2017 1 次提交
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由 Steven Rostedt (VMware) 提交于
When two function probes are added to set_ftrace_filter, and then one of them is removed, the update to the function locations is not performed, and the record keeping of the function states are corrupted, and causes an ftrace_bug() to occur. This is easily reproducable by adding two probes, removing one, and then adding it back again. # cd /sys/kernel/debug/tracing # echo schedule:traceoff > set_ftrace_filter # echo do_IRQ:traceoff > set_ftrace_filter # echo \!do_IRQ:traceoff > /debug/tracing/set_ftrace_filter # echo do_IRQ:traceoff > set_ftrace_filter Causes: ------------[ cut here ]------------ WARNING: CPU: 2 PID: 1098 at kernel/trace/ftrace.c:2369 ftrace_get_addr_curr+0x143/0x220 Modules linked in: [...] CPU: 2 PID: 1098 Comm: bash Not tainted 4.10.0-test+ #405 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012 Call Trace: dump_stack+0x68/0x9f __warn+0x111/0x130 ? trace_irq_work_interrupt+0xa0/0xa0 warn_slowpath_null+0x1d/0x20 ftrace_get_addr_curr+0x143/0x220 ? __fentry__+0x10/0x10 ftrace_replace_code+0xe3/0x4f0 ? ftrace_int3_handler+0x90/0x90 ? printk+0x99/0xb5 ? 0xffffffff81000000 ftrace_modify_all_code+0x97/0x110 arch_ftrace_update_code+0x10/0x20 ftrace_run_update_code+0x1c/0x60 ftrace_run_modify_code.isra.48.constprop.62+0x8e/0xd0 register_ftrace_function_probe+0x4b6/0x590 ? ftrace_startup+0x310/0x310 ? debug_lockdep_rcu_enabled.part.4+0x1a/0x30 ? update_stack_state+0x88/0x110 ? ftrace_regex_write.isra.43.part.44+0x1d3/0x320 ? preempt_count_sub+0x18/0xd0 ? mutex_lock_nested+0x104/0x800 ? ftrace_regex_write.isra.43.part.44+0x1d3/0x320 ? __unwind_start+0x1c0/0x1c0 ? _mutex_lock_nest_lock+0x800/0x800 ftrace_trace_probe_callback.isra.3+0xc0/0x130 ? func_set_flag+0xe0/0xe0 ? __lock_acquire+0x642/0x1790 ? __might_fault+0x1e/0x20 ? trace_get_user+0x398/0x470 ? strcmp+0x35/0x60 ftrace_trace_onoff_callback+0x48/0x70 ftrace_regex_write.isra.43.part.44+0x251/0x320 ? match_records+0x420/0x420 ftrace_filter_write+0x2b/0x30 __vfs_write+0xd7/0x330 ? do_loop_readv_writev+0x120/0x120 ? locks_remove_posix+0x90/0x2f0 ? do_lock_file_wait+0x160/0x160 ? __lock_is_held+0x93/0x100 ? rcu_read_lock_sched_held+0x5c/0xb0 ? preempt_count_sub+0x18/0xd0 ? __sb_start_write+0x10a/0x230 ? vfs_write+0x222/0x240 vfs_write+0xef/0x240 SyS_write+0xab/0x130 ? SyS_read+0x130/0x130 ? trace_hardirqs_on_caller+0x182/0x280 ? trace_hardirqs_on_thunk+0x1a/0x1c entry_SYSCALL_64_fastpath+0x18/0xad RIP: 0033:0x7fe61c157c30 RSP: 002b:00007ffe87890258 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: ffffffff8114a410 RCX: 00007fe61c157c30 RDX: 0000000000000010 RSI: 000055814798f5e0 RDI: 0000000000000001 RBP: ffff8800c9027f98 R08: 00007fe61c422740 R09: 00007fe61ca53700 R10: 0000000000000073 R11: 0000000000000246 R12: 0000558147a36400 R13: 00007ffe8788f160 R14: 0000000000000024 R15: 00007ffe8788f15c ? trace_hardirqs_off_caller+0xc0/0x110 ---[ end trace 99fa09b3d9869c2c ]--- Bad trampoline accounting at: ffffffff81cc3b00 (do_IRQ+0x0/0x150) Cc: stable@vger.kernel.org Fixes: 59df055f ("ftrace: trace different functions with a different tracer") Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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- 11 4月, 2017 6 次提交
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由 Steven Rostedt (VMware) 提交于
Stack tracing discovered that there's a small location inside the RCU infrastructure where calling rcu_irq_enter() does not work. As trace events use rcu_irq_enter() it must make sure that it is functionable. A check against rcu_irq_enter_disabled() is added with a WARN_ON_ONCE() as no trace event should ever be used in that part of RCU. If the warning is triggered, then the trace event is ignored. Restructure the __DO_TRACE() a bit to get rid of the prercu and postrcu, and just have an rcucheck that does the work from within the _DO_TRACE() macro. gcc optimization will compile out the rcucheck=0 case. Link: http://lkml.kernel.org/r/20170405093207.404f8deb@gandalf.local.homeAcked-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
Tracing uses rcu_irq_enter() as a way to make sure that RCU is watching when it needs to use rcu_read_lock() and friends. This is because tracing can happen as RCU is about to enter user space, or about to go idle, and RCU does not watch for RCU read side critical sections as it makes the transition. There is a small location within the RCU infrastructure that rcu_irq_enter() itself will not work. If tracing were to occur in that section it will break if it tries to use rcu_irq_enter(). Originally, this happens with the stack_tracer, because it will call save_stack_trace when it encounters stack usage that is greater than any stack usage it had encountered previously. There was a case where that happened in the RCU section where rcu_irq_enter() did not work, and lockdep complained loudly about it. To fix it, stack tracing added a call to be disabled and RCU would disable stack tracing during the critical section that rcu_irq_enter() was inoperable. This solution worked, but there are other cases that use rcu_irq_enter() and it would be a good idea to let RCU give a way to let others know that rcu_irq_enter() will not work. For example, in trace events. Another helpful aspect of this change is that it also moves the per cpu variable called in the RCU critical section into a cache locale along with other RCU per cpu variables used in that same location. I'm keeping the stack_trace_disable() code, as that still could be used in the future by places that really need to disable it. And since it's only a static inline, it wont take up any kernel text if it is not used. Link: http://lkml.kernel.org/r/20170405093207.404f8deb@gandalf.local.homeAcked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Paul E. McKenney 提交于
The tracing subsystem started using rcu_irq_entry() and rcu_irq_exit() (with my blessing) to allow the current _rcuidle alternative tracepoint name to be dispensed with while still maintaining good performance. Unfortunately, this causes RCU's dyntick-idle entry code's tracing to appear to RCU like an interrupt that occurs where RCU is not designed to handle interrupts. This commit fixes this problem by moving the zeroing of ->dynticks_nesting after the offending trace_rcu_dyntick() statement, which narrows the window of vulnerability to a pair of adjacent statements that are now marked with comments to that effect. Link: http://lkml.kernel.org/r/20170405093207.404f8deb@gandalf.local.home Link: http://lkml.kernel.org/r/20170405193928.GM1600@linux.vnet.ibm.comReported-by: NSteven Rostedt <rostedt@goodmis.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
In order to eliminate a function call, make "trace_active" into "disable_stack_tracer" and convert stack_tracer_disable() and friends into static inline functions. Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
There are certain parts of the kernel that cannot let stack tracing proceed (namely in RCU), because the stack tracer uses RCU, and parts of RCU internals cannot handle having RCU read side locks taken. Add stack_tracer_disable() and stack_tracer_enable() functions to let RCU stop stack tracing on the current CPU when it is in those critical sections. Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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由 Steven Rostedt (VMware) 提交于
The updates to the trace_active per cpu variable can be updated with the __this_cpu_*() functions as it only gets updated on the CPU that the variable is on. Thanks to Paul McKenney for suggesting __this_cpu_* instead of this_cpu_*. Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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- 07 4月, 2017 1 次提交
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由 Steven Rostedt (VMware) 提交于
The function tracer needs to be more careful than other subsystems when it comes to freeing data. Especially if that data is actually executable code. When a single function is traced, a trampoline can be dynamically allocated which is called to jump to the function trace callback. When the callback is no longer needed, the dynamic allocated trampoline needs to be freed. This is where the issues arise. The dynamically allocated trampoline must not be used again. As function tracing can trace all subsystems, including subsystems that are used to serialize aspects of freeing (namely RCU), it must take extra care when doing the freeing. Before synchronize_rcu_tasks() was around, there was no way for the function tracer to know that nothing was using the dynamically allocated trampoline when CONFIG_PREEMPT was enabled. That's because a task could be indefinitely preempted while sitting on the trampoline. Now with synchronize_rcu_tasks(), it will wait till all tasks have either voluntarily scheduled (not on the trampoline) or goes into userspace (not on the trampoline). Then it is safe to free the trampoline even with CONFIG_PREEMPT set. Acked-by: N"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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- 04 4月, 2017 1 次提交
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由 Alban Crequy 提交于
When a kretprobe is installed on a kernel function, there is a maximum limit of how many calls in parallel it can catch (aka "maxactive"). A kernel module could call register_kretprobe() and initialize maxactive (see example in samples/kprobes/kretprobe_example.c). But that is not exposed to userspace and it is currently not possible to choose maxactive when writing to /sys/kernel/debug/tracing/kprobe_events The default maxactive can be as low as 1 on single-core with a non-preemptive kernel. This is too low and we need to increase it not only for recursive functions, but for functions that sleep or resched. This patch updates the format of the command that can be written to kprobe_events so that maxactive can be optionally specified. I need this for a bpf program attached to the kretprobe of inet_csk_accept, which can sleep for a long time. This patch includes a basic selftest: > # ./ftracetest -v test.d/kprobe/ > === Ftrace unit tests === > [1] Kprobe dynamic event - adding and removing [PASS] > [2] Kprobe dynamic event - busy event check [PASS] > [3] Kprobe dynamic event with arguments [PASS] > [4] Kprobes event arguments with types [PASS] > [5] Kprobe dynamic event with function tracer [PASS] > [6] Kretprobe dynamic event with arguments [PASS] > [7] Kretprobe dynamic event with maxactive [PASS] > > # of passed: 7 > # of failed: 0 > # of unresolved: 0 > # of untested: 0 > # of unsupported: 0 > # of xfailed: 0 > # of undefined(test bug): 0 BugLink: https://github.com/iovisor/bcc/issues/1072 Link: http://lkml.kernel.org/r/1491215782-15490-1-git-send-email-alban@kinvolk.ioAcked-by: NMasami Hiramatsu <mhiramat@kernel.org> Signed-off-by: NAlban Crequy <alban@kinvolk.io> Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
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