linux/kernel/trace/trace.c, branch v5.5

tracing: Do not set trace clock if tracefs lockdown is in effect

2020-01-20T21:18:14Z

When trace_clock option is not set and unstable clcok detected, tracing_set_default_clock() sets trace_clock(ThinkPad A285 is one of case). In that case, if lockdown is in effect, null pointer dereference error happens in ring_buffer_set_clock(). Link: http://lkml.kernel.org/r/20200116131236.3866925-1-masami256@gmail.com Cc: stable@vger.kernel.org Fixes: 17911ff38aa58 ("tracing: Add locked_down checks to the open calls of files created for tracefs") Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1788488 Signed-off-by: Masami Ichikawa Signed-off-by: Steven Rostedt (VMware)

tracing: Fix lock inversion in trace_event_enable_tgid_record()

2019-12-21T21:05:13Z

Task T2 Task T3 trace_options_core_write() subsystem_open() mutex_lock(trace_types_lock) mutex_lock(event_mutex) set_tracer_flag() trace_event_enable_tgid_record() mutex_lock(trace_types_lock) mutex_lock(event_mutex) This gives a circular dependency deadlock between trace_types_lock and event_mutex. To fix this invert the usage of trace_types_lock and event_mutex in trace_options_core_write(). This keeps the sequence of lock usage consistent. Link: http://lkml.kernel.org/r/0101016eef175e38-8ca71caf-a4eb-480d-a1e6-6f0bbc015495-000000@us-west-2.amazonses.com Cc: stable@vger.kernel.org Fixes: d914ba37d7145 ("tracing: Add support for recording tgid of tasks") Signed-off-by: Prateek Sood Signed-off-by: Steven Rostedt (VMware)

Fix up for "printk: Drop pr_warning definition"

2019-12-06T09:02:35Z

Link: http://lkml.kernel.org/r/20191206092503.303d6a57@canb.auug.org.au Cc: Linux Next Mailing List Cc: Linux Kernel Mailing List Cc: "Steven Rostedt (VMware)" Cc: Kefeng Wang Cc: Linus Torvalds Signed-off-by: Stephen Rothwell Signed-off-by: Petr Mladek

tracing: Do not create directories if lockdown is in affect

2019-12-04T13:27:15Z

If lockdown is disabling tracing on boot up, it prevents the tracing files from even bering created. But when that happens, there's several places that will give a warning that the files were not created as that is usually a sign of a bug. Add in strategic locations where a check is made to see if tracing is disabled by lockdown, and if it is, do not go further, and fail silently (but print that tracing is disabled by lockdown, without doing a WARN_ON()). Cc: Matthew Garrett Fixes: 17911ff38aa5 ("tracing: Add locked_down checks to the open calls of files created for tracefs") Signed-off-by: Steven Rostedt (VMware)

tracing: Adding new functions for kernel access to Ftrace instances

2019-11-23T00:41:08Z

Adding 2 new functions - 1) struct trace_array *trace_array_get_by_name(const char *name); Return pointer to a trace array with given name. If it does not exist, create and return pointer to the new trace array. 2) int trace_array_set_clr_event(struct trace_array *tr, const char *system ,const char *event, bool enable); Enable/Disable events to this trace array. Additionally, - To handle reference counters, export trace_array_put() - Due to introduction of the above 2 new functions, we no longer need to export - ftrace_set_clr_event & trace_array_create APIs. Link: http://lkml.kernel.org/r/1574276919-11119-2-git-send-email-divya.indi@oracle.com Signed-off-by: Divya Indi Reviewed-by: Aruna Ramakrishna Signed-off-by: Steven Rostedt (VMware)

tracing: use kvcalloc for tgid_map array allocation

2019-11-14T18:15:11Z

Fail to allocate memory for tgid_map, because it requires order-6 page. detail as: c3 sh: page allocation failure: order:6, mode:0x140c0c0(GFP_KERNEL), nodemask=(null) c3 sh cpuset=/ mems_allowed=0 c3 CPU: 3 PID: 5632 Comm: sh Tainted: G W O 4.14.133+ #10 c3 Hardware name: Generic DT based system c3 Backtrace: c3 [] (dump_backtrace) from [](show_stack+0x18/0x1c) c3 [] (show_stack) from [](dump_stack+0x84/0xa4) c3 [] (dump_stack) from [](warn_alloc+0xc4/0x19c) c3 [] (warn_alloc) from [](__alloc_pages_nodemask+0xd18/0xf28) c3 [] (__alloc_pages_nodemask) from [](kmalloc_order+0x20/0x38) c3 [] (kmalloc_order) from [](kmalloc_order_trace+0x24/0x108) c3 [] (kmalloc_order_trace) from [](set_tracer_flag+0xb0/0x158) c3 [] (set_tracer_flag) from [](trace_options_core_write+0x7c/0xcc) c3 [] (trace_options_core_write) from [](__vfs_write+0x40/0x14c) c3 [] (__vfs_write) from [](vfs_write+0xc4/0x198) c3 [] (vfs_write) from [](SyS_write+0x6c/0xd0) c3 [] (SyS_write) from [](ret_fast_syscall+0x0/0x54) Switch to use kvcalloc to avoid unexpected allocation failures. Link: http://lkml.kernel.org/r/1571888070-24425-1-git-send-email-chunyan.zhang@unisoc.com Signed-off-by: Yuming Han Signed-off-by: Chunyan Zhang Signed-off-by: Steven Rostedt (VMware)

tracing: Adding NULL checks for trace_array descriptor pointer

2019-11-13T14:37:29Z

As part of commit f45d1225adb0 ("tracing: Kernel access to Ftrace instances") we exported certain functions. Here, we are adding some additional NULL checks to ensure safe usage by users of these APIs. Link: http://lkml.kernel.org/r/1565805327-579-4-git-send-email-divya.indi@oracle.com Signed-off-by: Divya Indi Signed-off-by: Steven Rostedt (VMware)

tracing: Verify if trace array exists before destroying it.

2019-11-13T14:37:29Z

A trace array can be destroyed from userspace or kernel. Verify if the trace array exists before proceeding to destroy/remove it. Link: http://lkml.kernel.org/r/1565805327-579-3-git-send-email-divya.indi@oracle.com Reviewed-by: Aruna Ramakrishna Signed-off-by: Divya Indi [ Removed unneeded braces ] Signed-off-by: Steven Rostedt (VMware)

tracing: Use CONFIG_PREEMPTION

2019-11-13T14:37:28Z

CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same functionality which today depends on CONFIG_PREEMPT. Add additional header output for PREEMPT_RT. Link: http://lkml.kernel.org/r/20191015191821.11479-34-bigeasy@linutronix.de Cc: Ingo Molnar Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt (VMware)

ftrace: Implement fs notification for tracing_max_latency

2019-11-13T14:37:28Z

This patch implements the feature that the tracing_max_latency file, e.g. /sys/kernel/debug/tracing/tracing_max_latency will receive notifications through the fsnotify framework when a new latency is available. One particularly interesting use of this facility is when enabling threshold tracing, through /sys/kernel/debug/tracing/tracing_thresh, together with the preempt/irqsoff tracers. This makes it possible to implement a user space program that can, with equal probability, obtain traces of latencies that occur immediately after each other in spite of the fact that the preempt/irqsoff tracers operate in overwrite mode. This facility works with the hwlat, preempt/irqsoff, and wakeup tracers. The tracers may call the latency_fsnotify() from places such as __schedule() or do_idle(); this makes it impossible to call queue_work() directly without risking a deadlock. The same would happen with a softirq, kernel thread or tasklet. For this reason we use the irq_work mechanism to call queue_work(). This patch creates a new workqueue. The reason for doing this is that I wanted to use the WQ_UNBOUND and WQ_HIGHPRI flags. My thinking was that WQ_UNBOUND might help with the latency in some important cases. If we use: queue_work(system_highpri_wq, &tr->fsnotify_work); then the work will (almost) always execute on the same CPU but if we are unlucky that CPU could be too busy while there could be another CPU in the system that would be able to process the work soon enough. queue_work_on() could be used to queue the work on another CPU but it seems difficult to select the right CPU. Link: http://lkml.kernel.org/r/20191008220824.7911-2-viktor.rosendahl@gmail.com Reviewed-by: Joel Fernandes (Google) Signed-off-by: Viktor Rosendahl (BMW) [ Added max() to have one compare for max latency ] Signed-off-by: Steven Rostedt (VMware)