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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-04-26 10:42:25 -0700
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-09-16 02:59:58 +0200
commit778935778c3b88e5152a88765850009006ef2e32 (patch)
treeaea593ef003a5b5c6175f65252e96aad3c6f6697
parent9395452b4aab7bc2475ef8935b4a4fb99d778d70 (diff)
downloadlinux-stericsson-778935778c3b88e5152a88765850009006ef2e32.tar.gz
PM / runtime: Use _rcuidle for runtime suspend tracepoints
Further testing with false negatives suppressed by commit 293e2421fe25 ("rcu: Remove superfluous versions of rcu_read_lock_sched_held()") identified a few more unprotected uses of RCU from the idle loop. Because RCU actively ignores idle-loop code (for energy-efficiency reasons, among other things), using RCU from the idle loop can result in too-short grace periods, in turn resulting in arbitrary misbehavior. The affected function is rpm_suspend(). The resulting lockdep-RCU splat is as follows: ------------------------------------------------------------------------ Warning from omap3 =============================== [ INFO: suspicious RCU usage. ] 4.6.0-rc5-next-20160426+ #1112 Not tainted ------------------------------- include/trace/events/rpm.h:63 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! 1 lock held by swapper/0/0: #0: (&(&dev->power.lock)->rlock){-.-...}, at: [<c052ee24>] __pm_runtime_suspend+0x54/0x84 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc5-next-20160426+ #1112 Hardware name: Generic OMAP36xx (Flattened Device Tree) [<c0110308>] (unwind_backtrace) from [<c010c3a8>] (show_stack+0x10/0x14) [<c010c3a8>] (show_stack) from [<c047fec8>] (dump_stack+0xb0/0xe4) [<c047fec8>] (dump_stack) from [<c052d7b4>] (rpm_suspend+0x604/0x7e4) [<c052d7b4>] (rpm_suspend) from [<c052ee34>] (__pm_runtime_suspend+0x64/0x84) [<c052ee34>] (__pm_runtime_suspend) from [<c04bf3bc>] (omap2_gpio_prepare_for_idle+0x5c/0x70) [<c04bf3bc>] (omap2_gpio_prepare_for_idle) from [<c01255e8>] (omap_sram_idle+0x140/0x244) [<c01255e8>] (omap_sram_idle) from [<c0126b48>] (omap3_enter_idle_bm+0xfc/0x1ec) [<c0126b48>] (omap3_enter_idle_bm) from [<c0601db8>] (cpuidle_enter_state+0x80/0x3d4) [<c0601db8>] (cpuidle_enter_state) from [<c0183c74>] (cpu_startup_entry+0x198/0x3a0) [<c0183c74>] (cpu_startup_entry) from [<c0b00c0c>] (start_kernel+0x354/0x3c8) [<c0b00c0c>] (start_kernel) from [<8000807c>] (0x8000807c) ------------------------------------------------------------------------ Reported-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Guenter Roeck <linux@roeck-us.net> [ rjw: Subject ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r--drivers/base/power/runtime.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 17995fadebd7..82a081ea4317 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -419,7 +419,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
struct device *parent = NULL;
int retval;
- trace_rpm_suspend(dev, rpmflags);
+ trace_rpm_suspend_rcuidle(dev, rpmflags);
repeat:
retval = rpm_check_suspend_allowed(dev);
@@ -549,7 +549,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
}
out:
- trace_rpm_return_int(dev, _THIS_IP_, retval);
+ trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
return retval;