timer_expire_entry.patch

   1 commit b258b549a9bc218a08c102ba54aac2c1d477b45a
   2 Author: Kienan Stewart <kstewart@efficios.com>
   3 Date:   Mon Apr 15 09:25:26 2024 -0400
   4
   5     Fix: timer_expire_entry changed in 4.19.312
   6
   7     See upstream commit:
   8
   9         commit bbb5b1c060d73ca96ccc8cceaa81f5e1a96e8fa4
  10         Author: Anna-Maria Gleixner <anna-maria@linutronix.de>
  11         Date:   Thu Mar 21 13:09:21 2019 +0100
  12
  13             timer/trace: Improve timer tracing
  14
  15             [ Upstream commit f28d3d5346e97e60c81f933ac89ccf015430e5cf ]
  16
  17             Timers are added to the timer wheel off by one. This is required in
  18             case a timer is queued directly before incrementing jiffies to prevent
  19             early timer expiry.
  20
  21             When reading a timer trace and relying only on the expiry time of the timer
  22             in the timer_start trace point and on the now in the timer_expiry_entry
  23             trace point, it seems that the timer fires late. With the current
  24             timer_expiry_entry trace point information only now=jiffies is printed but
  25             not the value of base->clk. This makes it impossible to draw a conclusion
  26             to the index of base->clk and makes it impossible to examine timer problems
  27             without additional trace points.
  28
  29             Therefore add the base->clk value to the timer_expire_entry trace
  30             point, to be able to calculate the index the timer base is located at
  31             during collecting expired timers.
  32
  33     Change-Id: I2ebdbb637db0966ff51f45bf66916a59a496b50c
  34     Signed-off-by: Kienan Stewart <kstewart@efficios.com>
  35     Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  36
  37 diff --git a/include/instrumentation/events/timer.h b/include/instrumentation/events/timer.h
  38 index bd21c037..77c4111a 100644
  39 --- a/include/instrumentation/events/timer.h
  40 +++ b/include/instrumentation/events/timer.h
  41 @@ -112,6 +112,7 @@ LTTNG_TRACEPOINT_EVENT(timer_start,
  42  #endif
  43
  44  #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,2,0) || \
  45 +       LTTNG_KERNEL_RANGE(4,19,312, 4,20,0) || \
  46         LTTNG_RHEL_KERNEL_RANGE(4,18,0,193,0,0, 4,19,0,0,0,0))
  47  /**
  48   * timer_expire_entry - called immediately before the timer callback