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  • Steven Rostedt (Red Hat)'s avatar
    tracing: Fix check for cpu online when event is disabled · dc17147d
    Steven Rostedt (Red Hat) authored
    Commit f3775549 ("tracepoints: Do not trace when cpu is offline") added
    a check to make sure that tracepoints only get called when the cpu is
    online, as it uses rcu_read_lock_sched() for protection.
    
    Commit 3a630178 ("tracing: generate RCU warnings even when tracepoints
    are disabled") added lockdep checks (including rcu checks) for events that
    are not enabled to catch possible RCU issues that would only be triggered if
    a trace event was enabled. Commit f3775549 only stopped the warnings
    when the trace event was enabled but did not prevent warnings if the trace
    event was called when disabled.
    
    To fix this, the cpu online check is moved to where the condition is added
    to the trace event. This will place the cpu online check in all places that
    it may be used now and in the future.
    
    Cc: stable@vger.kernel.org # v3.18+
    Fixes: f3775549 ("tracepoints: Do not trace when cpu is offline")
    Fixes: 3a630178
    
     ("tracing: generate RCU warnings even when tracepoints are disabled")
    Reported-by: default avatarSudeep Holla <sudeep.holla@arm.com>
    Tested-by: default avatarSudeep Holla <sudeep.holla@arm.com>
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    dc17147d