From dab37f9594b9af44bd3f9b6a24e8699da1116faa Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Tue, 25 Feb 2020 10:18:11 -0500 Subject: [PATCH] Fix: rcu: Fix data-race due to atomic_t copy-by-value (5.5.6, 5.4.22) The following upstream commit has been backported to stable kernels 5.5.6 and 5.4.22: commit 6cf539a87a61a4fbc43f625267dbcbcf283872ed Author: Marco Elver Date: Wed Oct 9 17:57:43 2019 +0200 rcu: Fix data-race due to atomic_t copy-by-value This fixes a data-race where `atomic_t dynticks` is copied by value. The copy is performed non-atomically, resulting in a data-race if `dynticks` is updated concurrently. Signed-off-by: Mathieu Desnoyers --- instrumentation/events/lttng-module/rcu.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/instrumentation/events/lttng-module/rcu.h b/instrumentation/events/lttng-module/rcu.h index 123f6151..70acdf1c 100644 --- a/instrumentation/events/lttng-module/rcu.h +++ b/instrumentation/events/lttng-module/rcu.h @@ -385,7 +385,9 @@ LTTNG_TRACEPOINT_EVENT(rcu_fqs, * events use the upper bits of each number, while interrupt-related * events use the lower bits. */ -#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) +#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) \ + || LTTNG_KERNEL_RANGE(5,5,6, 5,6,0) \ + || LTTNG_KERNEL_RANGE(5,4,22, 5,5,0) LTTNG_TRACEPOINT_EVENT(rcu_dyntick, TP_PROTO(const char *polarity, long oldnesting, long newnesting, int dynticks), -- 2.34.1