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2de780dfbe
linux/kernel/trace
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Steven Rostedt (VMware) 2de780dfbe ftrace: Handle tracing when switching between context 
commit 726b3d3f14 upstream.

When an interrupt or NMI comes in and switches the context, there's a delay
from when the preempt_count() shows the update. As the preempt_count() is
used to detect recursion having each context have its own bit get set when
tracing starts, and if that bit is already set, it is considered a recursion
and the function exits. But if this happens in that section where context
has changed but preempt_count() has not been updated, this will be
incorrectly flagged as a recursion.

To handle this case, create another bit call TRANSITION and test it if the
current context bit is already set. Flag the call as a recursion if the
TRANSITION bit is already set, and if not, set it and continue. The
TRANSITION bit will be cleared normally on the return of the function that
set it, or if the current context bit is clear, set it and clear the
TRANSITION bit to allow for another transition between the current context
and an even higher one.

Cc: stable@vger.kernel.org
Fixes: edc15cafcb ("tracing: Avoid unnecessary multiple recursion checks")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-10 12:35:58 +01:00
..
blktrace.c blktrace: fix debugfs use after free 2020-11-10 12:35:54 +01:00
bpf_trace.c bpf: fix nested bpf tracepoints with per-cpu data 2019-07-03 13:14:48 +02:00
ftrace.c ftrace: Move RCU is watching check after recursion check 2020-10-07 08:00:05 +02:00
Kconfig Stop the ad-hoc games with -Wno-maybe-initialized 2020-05-20 08:18:45 +02:00
Makefile tracing: Allow gcov profiling on only ftrace subsystem 2018-08-21 09:11:49 -04:00
power-traces.c
preemptirq_delay_test.c tracing: Use trace_clock_local() for looping in preemptirq_delay_test.c 2018-10-17 15:35:33 -04:00
ring_buffer_benchmark.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
ring_buffer.c ring-buffer: Fix recursion protection transitions between interrupt context 2020-11-10 12:35:58 +01:00
rpm-traces.c
trace_benchmark.c rcu: Rename cond_resched_rcu_qs() to cond_resched_tasks_rcu_qs() 2018-05-15 10:27:29 -07:00
trace_benchmark.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_branch.c Revert "x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP" 2019-07-03 13:14:41 +02:00
trace_clock.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_entries.h tracing: Set kernel_stack's caller size properly 2020-10-01 13:14:31 +02:00
trace_event_perf.c tracing: Fix race in perf_trace_buf initialization 2019-10-29 09:20:03 +01:00
trace_events_filter_test.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_events_filter.c tracing: Have error path in predicate_parse() free its allocated memory 2020-08-05 10:05:59 +02:00
trace_events_hist.c tracing: fix double free 2020-10-01 13:14:53 +02:00
trace_events_trigger.c tracing: Fix event trigger to accept redundant spaces 2020-06-30 23:17:17 -04:00
trace_events.c tracing: Adding NULL checks for trace_array descriptor pointer 2020-10-01 13:14:27 +02:00
trace_export.c tracing: Add trigger file for trace_markers tracefs/ftrace/print 2018-05-29 08:28:53 -04:00
trace_functions_graph.c tracing/fgraph: Fix set_graph_function from showing interrupts 2018-12-08 12:59:07 +01:00
trace_functions.c tracing: Update stack trace skipping for ORC unwinder 2018-01-23 15:57:00 -05:00
trace_hwlat.c tracing/hwlat: Honor the tracing_cpumask 2020-08-21 11:05:33 +02:00
trace_irqsoff.c tracing/fgraph: Fix set_graph_function from showing interrupts 2018-12-08 12:59:07 +01:00
trace_kdb.c tracing: Silence GCC 9 array bounds warning 2019-06-25 11:35:52 +08:00
trace_kprobe_selftest.c selftest/ftrace: Move kprobe selftest function to separate compile unit 2018-07-30 18:41:04 -04:00
trace_kprobe_selftest.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_kprobe.c tracing/kprobes: Fix a double initialization typo 2020-05-14 07:57:16 +02:00
trace_mmiotrace.c
trace_nop.c
trace_output.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_output.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_preemptirq.c lockdep: fix order in trace_hardirqs_off_caller() 2020-10-01 13:14:50 +02:00
trace_printk.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_probe.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_probe.h tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_sched_switch.c tracing: Fix sched switch start/stop refcount racy updates 2020-02-11 04:33:55 -08:00
trace_sched_wakeup.c kernel/trace: Fix do not unregister tracepoints when register sched_migrate_task fail 2020-01-14 20:06:59 +01:00
trace_selftest_dynamic.c ftrace: Mark function tracer test functions noinline/noclone 2018-01-23 15:57:29 -05:00
trace_selftest.c ftrace: Handle tracing when switching between context 2020-11-10 12:35:58 +01:00
trace_seq.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_stack.c tracing: Have stack tracer compile when MCOUNT_INSN_SIZE is not defined 2020-01-14 20:06:59 +01:00
trace_stat.c tracing: Fix very unlikely race of registering two stat tracers 2020-02-24 08:34:39 +01:00
trace_stat.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_syscalls.c Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
trace_uprobe.c tracing/uprobes: Fix output for multiple string arguments 2019-02-20 10:25:48 +01:00
trace.c tracing: Use address-of operator on section symbols 2020-10-01 13:14:38 +02:00
trace.h ftrace: Handle tracing when switching between context 2020-11-10 12:35:58 +01:00
tracing_map.c tracing: Have the histogram compare functions convert to u64 first 2020-01-09 10:19:02 +01:00
tracing_map.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00