- 30 Jan, 2020 13 commits
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Tom Zanussi authored
Have trace_boot_add_kprobe_event() use the kprobe_event interface. Also, rename kprobe_event_run_cmd() to kprobe_event_run_command() now that trace_boot's version is gone. Link: http://lkml.kernel.org/r/af5429d11291ab1e9a85a0ff944af3b2bcf193c7.1580323897.git.zanussi@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add functions used to generate kprobe event commands, built on top of the dynevent_cmd interface. kprobe_event_gen_cmd_start() is used to create a kprobe event command using a variable arg list, and kretprobe_event_gen_cmd_start() does the same for kretprobe event commands. kprobe_event_add_fields() can be used to add single fields one by one or as a group. Once all desired fields are added, kprobe_event_gen_cmd_end() or kretprobe_event_gen_cmd_end() respectively are used to actually execute the command and create the event. Link: http://lkml.kernel.org/r/95cc4696502bb6017f9126f306a45ad19b4cc14f.1580323897.git.zanussi@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add a test module that checks the basic functionality of the in-kernel synthetic event generation API by generating and tracing synthetic events from a module. Link: http://lkml.kernel.org/r/fcb4dd9eb9eefb70ab20538d3529d51642389664.1580323897.git.zanussi@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add an exported function named synth_event_trace(), allowing modules or other kernel code to trace synthetic events. Also added are several functions that allow the same functionality to be broken out in a piecewise fashion, which are useful in situations where tracing an event from a full array of values would be cumbersome. Those functions are synth_event_trace_start/end() and synth_event_add_(next)_val(). Link: http://lkml.kernel.org/r/7a84de5f1854acf4144b57efe835ca645afa764f.1580323897.git.zanussi@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add functions used to generate synthetic event commands, built on top of the dynevent_cmd interface. synth_event_gen_cmd_start() is used to create a synthetic event command using a variable arg list and synth_event_gen_cmd_array_start() does the same thing but using an array of field descriptors. synth_event_add_field(), synth_event_add_field_str() and synth_event_add_fields() can be used to add single fields one by one or as a group. Once all desired fields are added, synth_event_gen_cmd_end() is used to actually execute the command and create the event. synth_event_create() does everything, including creating the event, in a single call. Link: http://lkml.kernel.org/r/38fef702fad5ef208009f459552f34a94befd860.1580323897.git.zanussi@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add an interface used to build up dynamic event creation commands, such as synthetic and kprobe events. Interfaces specific to those particular types of events and others can be built on top of this interface. Command creation is started by first using the dynevent_cmd_init() function to initialize the dynevent_cmd object. Following that, args are appended and optionally checked by the dynevent_arg_add() and dynevent_arg_pair_add() functions, which use objects representing arguments and pairs of arguments, initialized respectively by dynevent_arg_init() and dynevent_arg_pair_init(). Finally, once all args have been successfully added, the command is finalized and actually created using dynevent_create(). The code here for actually printing into the dyn_event->cmd buffer using snprintf() etc was adapted from v4 of Masami's 'tracing/boot: Add synthetic event support' patch. Link: http://lkml.kernel.org/r/1f65fa44390b6f238f6036777c3784ced1dcc6a0.1580323897.git.zanussi@kernel.orgSigned-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
create_or_delete_synth_event() contains code to delete a synthetic event, which would be useful on its own - specifically, it would be useful to allow event-creating modules to call it separately. Separate out the delete code from that function and create an exported function named synth_event_delete(). Link: http://lkml.kernel.org/r/050db3b06df7f0a4b8a2922da602d1d879c7c1c2.1580323897.git.zanussi@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add a function to get an event file and prevent it from going away on module or instance removal. trace_get_event_file() will find an event file in a given instance (if instance is NULL, it assumes the top trace array) and return it, pinning the instance's trace array as well as the event's module, if applicable, so they won't go away while in use. trace_put_event_file() does the matching release. Link: http://lkml.kernel.org/r/bb31ac4bdda168d5ed3c4b5f5a4c8f633e8d9118.1580323897.git.zanussi@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> [ Moved trace_array_put() to end of trace_put_event_file() ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add a new trace_array_find() function that can be used to find a trace array given the instance name, and replace existing code that does the same thing with it. Also add trace_array_find_get() which does the same but returns the trace array after upping its refcount. Also make both available for use outside of trace.c. Link: http://lkml.kernel.org/r/cb68528c975eba95bee4561ac67dd1499423b2e5.1580323897.git.zanussi@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Vasily Averin authored
if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Without patch: # dd bs=30 skip=1 if=/sys/kernel/tracing/events/sched/sched_switch/trigger dd: /sys/kernel/tracing/events/sched/sched_switch/trigger: cannot skip to specified offset n traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist # Available triggers: # traceon traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist 6+1 records in 6+1 records out 206 bytes copied, 0.00027916 s, 738 kB/s Notice the printing of "# Available triggers:..." after the line. With the patch: # dd bs=30 skip=1 if=/sys/kernel/tracing/events/sched/sched_switch/trigger dd: /sys/kernel/tracing/events/sched/sched_switch/trigger: cannot skip to specified offset n traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist 2+1 records in 2+1 records out 88 bytes copied, 0.000526867 s, 167 kB/s It only prints the end of the file, and does not restart. Link: http://lkml.kernel.org/r/3c35ee24-dd3a-8119-9c19-552ed253388a@virtuozzo.com https://bugzilla.kernel.org/show_bug.cgi?id=206283Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Vasily Averin authored
if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Link: http://lkml.kernel.org/r/7ad85b22-1866-977c-db17-88ac438bc764@virtuozzo.comSigned-off-by: Vasily Averin <vvs@virtuozzo.com> [ This is not a bug fix, it just makes it "technically correct" which is why I applied it. NULL is only returned on an anomaly which triggers a WARN_ON ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Vasily Averin authored
if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Without patch: # dd bs=4 skip=1 if=/sys/kernel/tracing/set_ftrace_pid dd: /sys/kernel/tracing/set_ftrace_pid: cannot skip to specified offset id no pid 2+1 records in 2+1 records out 10 bytes copied, 0.000213285 s, 46.9 kB/s Notice the "id" followed by "no pid". With the patch: # dd bs=4 skip=1 if=/sys/kernel/tracing/set_ftrace_pid dd: /sys/kernel/tracing/set_ftrace_pid: cannot skip to specified offset id 0+1 records in 0+1 records out 3 bytes copied, 0.000202112 s, 14.8 kB/s Notice that it only prints "id" and not the "no pid" afterward. Link: http://lkml.kernel.org/r/4f87c6ad-f114-30bb-8506-c32274ce2992@virtuozzo.com https://bugzilla.kernel.org/show_bug.cgi?id=206283Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Mathieu Desnoyers authored
Reading the sched_cmdline_ref and sched_tgid_ref initial state within tracing_start_sched_switch without holding the sched_register_mutex is racy against concurrent updates, which can lead to tracepoint probes being registered more than once (and thus trigger warnings within tracepoint.c). [ May be the fix for this bug ] Link: https://lore.kernel.org/r/000000000000ab6f84056c786b93@google.com Link: http://lkml.kernel.org/r/20190817141208.15226-1-mathieu.desnoyers@efficios.com Cc: stable@vger.kernel.org CC: Steven Rostedt (VMware) <rostedt@goodmis.org> CC: Joel Fernandes (Google) <joel@joelfernandes.org> CC: Peter Zijlstra <peterz@infradead.org> CC: Thomas Gleixner <tglx@linutronix.de> CC: Paul E. McKenney <paulmck@linux.ibm.com> Reported-by: syzbot+774fddf07b7ab29a1e55@syzkaller.appspotmail.com Fixes: d914ba37 ("tracing: Add support for recording tgid of tasks") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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- 29 Jan, 2020 7 commits
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Masami Hiramatsu authored
Move external function declarations into kernel/trace/trace.h from trace_boot.c for tracing subsystem internal use. Link: http://lkml.kernel.org/r/158029060405.12381.11944554430359702545.stgit@devnote2Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Masami Hiramatsu authored
Include some required (but currently indirectly included) headers and sort it alphabetically. Link: http://lkml.kernel.org/r/158029059514.12381.6597832266860248781.stgit@devnote2Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add a testcase ensuring that the tracing error_log correctly displays hist trigger parsing errors. Link: http://lkml.kernel.org/r/62ec58d9aca661cde46ba678e32a938427945e9e.1561743018.git.zanussi@kernel.orgReviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
The 'hist:' prefix gets stripped from the command text during command processing, but should be added back when displaying the command during error processing. Not only because it's what should be displayed but also because not having it means the test cases fail because the caret is miscalculated by the length of the prefix string. Link: http://lkml.kernel.org/r/449df721f560042e22382f67574bcc5b4d830d3d.1561743018.git.zanussi@kernel.orgReviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
Add error codes and messages for all the error paths leading to sort specification parsing errors. Link: http://lkml.kernel.org/r/237830dc05e583fbb53664d817a784297bf961be.1561743018.git.zanussi@kernel.orgReviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Tom Zanussi authored
In the process of adding better error messages for sorting, I realized that strsep was being used incorrectly and some of the error paths I was expecting to be hit weren't and just fell through to the common invalid key error case. It also became obvious that for keyword assignments, it wasn't necessary to save the full assignment and reparse it later, and having a common empty-assignment check would also make more sense in terms of error processing. Change the code to fix these problems and simplify it for new error message changes in a subsequent patch. Link: http://lkml.kernel.org/r/1c3ef0b6655deaf345f6faee2584a0298ac2d743.1561743018.git.zanussi@kernel.org Fixes: e62347d2 ("tracing: Add hist trigger support for user-defined sorting ('sort=' param)") Fixes: 7ef224d1 ("tracing: Add 'hist' event trigger command") Fixes: a4072fe8 ("tracing: Add a clock attribute for hist triggers") Reported-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Mauro Carvalho Chehab authored
Sphinx warnings about his: Documentation/trace/kprobetrace.rst:68: WARNING: undefined label: user_mem_access (if the link has no caption the label must precede a section header) The problem is quite simple: Sphinx wants a blank line after references. Link: http://lkml.kernel.org/r/a83ea390bc28784518fce772b4c961ea1c976f14.1560883872.git.mchehab+samsung@kernel.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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- 25 Jan, 2020 2 commits
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Steven Rostedt (VMware) authored
As warnings can trigger panics, especially when "panic_on_warn" is set, memory failure warnings can cause panics and fail fuzz testers that are stressing memory. Create a MEM_FAIL() macro to use instead of WARN() in the tracing code (perhaps this should be a kernel wide macro?), and use that for memory failure issues. This should stop failing fuzz tests due to warnings. Link: https://lore.kernel.org/r/CACT4Y+ZP-7np20GVRu3p+eZys9GPtbu+JpfV+HtsufAzvTgJrg@mail.gmail.comSuggested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Steven Rostedt (VMware) authored
The trace_array_get_by_name() creates a ftrace instance and trace_array_put() is used to remove the reference. Even though the trace_array_get_by_name() creates the instance, it also adds a reference count to it, that prevents user space from removing it. As the bootconfig just creates the instance on boot up, it should still be used where it can be deleted by user space after boot. A trace_array_put() is required to let that happen. Also, change the documentation on trace_array_get_by_name() to make this not be so confusing. Link: https://lore.kernel.org/r/20200124205927.76128804@rorschach.local.home Fixes: 4f712a4d ("tracing/boot: Add instance node support") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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- 24 Jan, 2020 5 commits
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Hou Pengyang authored
commit f42c85e7 moved tracepoint's ftrace creation into include/trace/ftrace.h and trace/define_trace.h was deleted as a result. However some comment info does not adapt to the change, which is such a misguiding when reading related code. This patch fix this by moving trace/trace_events.h to <trace/events/XXX.h>, since tracepoint headers have already been moved to tarce/events/. Link: http://lkml.kernel.org/r/1425419298-61941-1-git-send-email-houpengyang@huawei.comSigned-off-by: Hou Pengyang <houpengyang@huawei.com> [ Pulled from the archeological digging of my INBOX ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Dan Carpenter authored
We checked "iter->trace" earlier so there is no need to check here. Link: http://lkml.kernel.org/r/20141122183012.GB6994@mwandaSigned-off-by: Dan Carpenter <dan.carpenter@oracle.com> [ Pulled from the archeological digging of my INBOX ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Josef Bacik authored
I noticed when trying to use the trace-cmd python interface that reading the raw buffer wasn't working for kernel_stack events. This is because it uses a stubbed version of __dynamic_array that doesn't do the __data_loc trick and encode the length of the array into the field. Instead it just shows up as a size of 0. So change this to __array and set the len to FTRACE_STACK_ENTRIES since this is what we actually do in practice and matches how user_stack_trace works. Link: http://lkml.kernel.org/r/1411589652-1318-1-git-send-email-jbacik@fb.comSigned-off-by: Josef Bacik <jbacik@fb.com> [ Pulled from the archeological digging of my INBOX ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Luis Henriques authored
tracing_stat_init() was always returning '0', even on the error paths. It now returns -ENODEV if tracing_init_dentry() fails or -ENOMEM if it fails to created the 'trace_stat' debugfs directory. Link: http://lkml.kernel.org/r/1410299381-20108-1-git-send-email-luis.henriques@canonical.com Fixes: ed6f1c99 ("tracing: Check return value of tracing_init_dentry()") Signed-off-by: Luis Henriques <luis.henriques@canonical.com> [ Pulled from the archeological digging of my INBOX ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Steven Rostedt (VMware) authored
Looking through old emails in my INBOX, I came across a patch from Luis Henriques that attempted to fix a race of two stat tracers registering the same stat trace (extremely unlikely, as this is done in the kernel, and probably doesn't even exist). The submitted patch wasn't quite right as it needed to deal with clean up a bit better (if two stat tracers were the same, it would have the same files). But to make the code cleaner, all we needed to do is to keep the all_stat_sessions_mutex held for most of the registering function. Link: http://lkml.kernel.org/r/1410299375-20068-1-git-send-email-luis.henriques@canonical.com Fixes: 002bb86d ("tracing/ftrace: separate events tracing and stats tracing engine") Reported-by: Luis Henriques <luis.henriques@canonical.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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- 22 Jan, 2020 2 commits
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Alex Shi authored
This limitation are never lunched from introduce commit 970988e1 ("tracing/kprobe: Add kprobe_event= boot parameter") Could we remove it if no intention to implement it? Link: http://lkml.kernel.org/r/1579586075-45132-1-git-send-email-alex.shi@linux.alibaba.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Steven Rostedt (VMware) authored
If we exit due to a bad input to trace_printk() (highly unlikely), then the buffer variable will not be initialized when we unnest the ring buffer. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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- 21 Jan, 2020 9 commits
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Dan Carpenter authored
The trace_array_get_by_name() function doesn't return error pointers, it returns NULL on error. Link: http://lkml.kernel.org/r/20200117053007.5h2juv272pokqhtq@kili.mountain Fixes: 4f712a4d ("tracing/boot: Add instance node support") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Alex Shi authored
This macro isn't used from commit 3a161d99 ("tracing: Create seq_buf layer in trace_seq"). so no needs to keep it. Link: http://lkml.kernel.org/r/1579586086-45543-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: Alex Shi <alex.shi@linux.alibaba.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Alex Shi authored
This macro isn't used since commit d325c402 ("ring-buffer: Remove unused function ring_buffer_page_len()"), so better to remove it. Link: http://lkml.kernel.org/r/1579586080-45300-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: Alex Shi <alex.shi@linux.alibaba.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Colin Ian King authored
There are two spelling mistakes in printf statements, fix these. Link: http://lkml.kernel.org/r/20200116092206.52192-1-colin.king@canonical.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Masami Hiramatsu authored
Fix typos in boottime-trace.rst according to Randy's suggestions. Link: http://lkml.kernel.org/r/157949060335.25888.13153184562531693684.stgit@devnote2Suggested-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Masami Hiramatsu authored
Fix typos in bootconfig.rst according to Randy's suggestions. Link: http://lkml.kernel.org/r/157949059219.25888.16939971423610233631.stgit@devnote2Suggested-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Masami Hiramatsu authored
Fix Kconfig help message since the bootconfig file is only available to be appended to initramfs. And also add a reference to the documentation. Link: http://lkml.kernel.org/r/157949058031.25888.18399447161895787505.stgit@devnote2Reported-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Alex Shi authored
This macro isn't used from commit cb7be3b2 ("ftrace: remove daemon"). So no needs to keep it. Link: http://lkml.kernel.org/r/1579586063-44984-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: Alex Shi <alex.shi@linux.alibaba.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Alex Shi authored
These 2 macros aren't used from commit eee8ded1 ("ftrace: Have the function probes call their own function"), so remove them. Link: http://lkml.kernel.org/r/1579585807-43316-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: Alex Shi <alex.shi@linux.alibaba.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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- 16 Jan, 2020 1 commit
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Steven Rostedt (VMware) authored
trace_printk() is used to debug the kernel which includes the tracing infrastructure. But because it writes to the ring buffer, and so does much of the tracing infrastructure, the ring buffer's recursive detection will drop writes to the ring buffer that is in the same context as the current write is happening (it allows interrupts to write when normal context is writing, but wont let normal context write while normal context is writing). This can cause confusion and think that the code is where the trace_printk() exists is not hit. To solve this, up the recursive nesting of the ring buffer when trace_printk() is called before it writes to the buffer itself. Note, this does make it dangerous to use trace_printk() in the ring buffer code itself, because this basically disables the recursion protection of trace_printk() buffer writes. But as trace_printk() is only used for debugging, and if this does occur, the developer will see the cause real quick (recursive blowing up of the stack). Thus the developer can deal with that. But having trace_printk() silently ignored is a much bigger problem, and disabling recursive protection is a small price to pay to fix it. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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- 14 Jan, 2020 1 commit
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Steven Rostedt (VMware) authored
rb_update_event has changed without the kernel-doc update. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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