subject:"\[PATCH 4\/4\] rcu\: Fix dyntick\-idle tracing"

Re: [PATCH 4/4] rcu: Fix dyntick-idle tracing

2017-04-06 Thread kbuild test robot

Hi Paul,

[auto build test ERROR on tip/perf/core]
[also build test ERROR on v4.11-rc5 next-20170406]
[if your patch is applied to the wrong git tree, please drop us a note to help 
improve the system]

url:
https://github.com/0day-ci/linux/commits/Steven-Rostedt/tracing-Add-usecase-of-synchronize_rcu_tasks-and-stack_tracer_disable/20170407-122352
config: x86_64-randconfig-x009-201714 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64 

All errors (new ones prefixed by >>):

   kernel/rcu/tree.c: In function 'rcu_eqs_enter_common':
>> kernel/rcu/tree.c:806:2: error: implicit declaration of function 
>> 'stack_tracer_enable' [-Werror=implicit-function-declaration]
 stack_tracer_enable();
 ^~~
   cc1: some warnings being treated as errors

vim +/stack_tracer_enable +806 kernel/rcu/tree.c

   800  do_nocb_deferred_wakeup(rdp);
   801  }
   802  rcu_prepare_for_idle();
   803  stack_tracer_disable();
   804  rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */
   805  rcu_dynticks_eqs_enter(); /* After this, tracing works again. */
 > 806  stack_tracer_enable();
   807  rcu_dynticks_task_enter();
   808  
   809  /*

---
0-DAY kernel test infrastructureOpen Source Technology Center
https://lists.01.org/pipermail/kbuild-all   Intel Corporation


.config.gz
Description: application/gzip

Re: [PATCH 4/4] rcu: Fix dyntick-idle tracing

2017-04-06 Thread kbuild test robot

Hi Paul,

[auto build test ERROR on tip/perf/core]
[also build test ERROR on v4.11-rc5 next-20170406]
[if your patch is applied to the wrong git tree, please drop us a note to help 
improve the system]

url:
https://github.com/0day-ci/linux/commits/Steven-Rostedt/tracing-Add-usecase-of-synchronize_rcu_tasks-and-stack_tracer_disable/20170407-122352
config: x86_64-randconfig-x009-201714 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64 

All errors (new ones prefixed by >>):

   kernel/rcu/tree.c: In function 'rcu_eqs_enter_common':
>> kernel/rcu/tree.c:806:2: error: implicit declaration of function 
>> 'stack_tracer_enable' [-Werror=implicit-function-declaration]
 stack_tracer_enable();
 ^~~
   cc1: some warnings being treated as errors

vim +/stack_tracer_enable +806 kernel/rcu/tree.c

   800  do_nocb_deferred_wakeup(rdp);
   801  }
   802  rcu_prepare_for_idle();
   803  stack_tracer_disable();
   804  rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */
   805  rcu_dynticks_eqs_enter(); /* After this, tracing works again. */
 > 806  stack_tracer_enable();
   807  rcu_dynticks_task_enter();
   808  
   809  /*

---
0-DAY kernel test infrastructureOpen Source Technology Center
https://lists.01.org/pipermail/kbuild-all   Intel Corporation


.config.gz
Description: application/gzip

Re: [PATCH 4/4] rcu: Fix dyntick-idle tracing

2017-04-06 Thread Paul E. McKenney

On Thu, Apr 06, 2017 at 12:42:41PM -0400, Steven Rostedt wrote:
> From: "Paul E. McKenney" 
> 
> The tracing subsystem started using rcu_irq_entry() and rcu_irq_exit()
> (with my blessing) to allow the current _rcuidle alternative tracepoint
> name to be dispensed with while still maintaining good performance.
> Unfortunately, this causes RCU's dyntick-idle entry code's tracing to
> appear to RCU like an interrupt that occurs where RCU is not designed
> to handle interrupts.
> 
> This commit fixes this problem by moving the zeroing of ->dynticks_nesting
> after the offending trace_rcu_dyntick() statement, which narrows the
> window of vulnerability to a pair of adjacent statements that are now
> marked with comments to that effect.
> 
> Link: http://lkml.kernel.org/r/20170405193928.gm1...@linux.vnet.ibm.com
> 
> Reported-by: Steven Rostedt 
> Signed-off-by: Paul E. McKenney 
> Signed-off-by: Steven Rostedt (VMware) 

Acked-by: Paul E. McKenney 

Really confirming my Signed-off-by given Steven's changes, but whatever.  ;-)

Thanx, Paul

> ---
>  kernel/rcu/tree.c | 48 +++-
>  1 file changed, 23 insertions(+), 25 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 50fee7689e71..8b4d273331e4 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -57,6 +57,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
> 
>  #include "tree.h"
>  #include "rcu.h"
> @@ -771,25 +772,24 @@ cpu_needs_another_gp(struct rcu_state *rsp, struct 
> rcu_data *rdp)
>  }
> 
>  /*
> - * rcu_eqs_enter_common - current CPU is moving towards extended quiescent 
> state
> + * rcu_eqs_enter_common - current CPU is entering an extended quiescent state
>   *
> - * If the new value of the ->dynticks_nesting counter now is zero,
> - * we really have entered idle, and must do the appropriate accounting.
> - * The caller must have disabled interrupts.
> + * Enter idle, doing appropriate accounting.  The caller must have
> + * disabled interrupts.
>   */
> -static void rcu_eqs_enter_common(long long oldval, bool user)
> +static void rcu_eqs_enter_common(bool user)
>  {
>   struct rcu_state *rsp;
>   struct rcu_data *rdp;
> - RCU_TRACE(struct rcu_dynticks *rdtp = this_cpu_ptr(_dynticks);)
> + struct rcu_dynticks *rdtp = this_cpu_ptr(_dynticks);
> 
> - trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
> + trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);
>   if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
>   !user && !is_idle_task(current)) {
>   struct task_struct *idle __maybe_unused =
>   idle_task(smp_processor_id());
> 
> - trace_rcu_dyntick(TPS("Error on entry: not idle task"), oldval, 
> 0);
> + trace_rcu_dyntick(TPS("Error on entry: not idle task"), 
> rdtp->dynticks_nesting, 0);
>   rcu_ftrace_dump(DUMP_ORIG);
>   WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
> current->pid, current->comm,
> @@ -800,7 +800,10 @@ static void rcu_eqs_enter_common(long long oldval, bool 
> user)
>   do_nocb_deferred_wakeup(rdp);
>   }
>   rcu_prepare_for_idle();
> - rcu_dynticks_eqs_enter();
> + stack_tracer_disable();
> + rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */
> + rcu_dynticks_eqs_enter(); /* After this, tracing works again. */
> + stack_tracer_enable();
>   rcu_dynticks_task_enter();
> 
>   /*
> @@ -821,19 +824,15 @@ static void rcu_eqs_enter_common(long long oldval, bool 
> user)
>   */
>  static void rcu_eqs_enter(bool user)
>  {
> - long long oldval;
>   struct rcu_dynticks *rdtp;
> 
>   rdtp = this_cpu_ptr(_dynticks);
> - oldval = rdtp->dynticks_nesting;
>   WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
> -  (oldval & DYNTICK_TASK_NEST_MASK) == 0);
> - if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) {
> - rdtp->dynticks_nesting = 0;
> - rcu_eqs_enter_common(oldval, user);
> - } else {
> +  (rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
> + if ((rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 
> DYNTICK_TASK_NEST_VALUE)
> + rcu_eqs_enter_common(user);
> + else
>   rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
> - }
>  }
> 
>  /**
> @@ -892,19 +891,18 @@ void rcu_user_enter(void)
>   */
>  void rcu_irq_exit(void)
>  {
> - long long oldval;
>   struct rcu_dynticks *rdtp;
> 
>   RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_exit() invoked with irqs 
> enabled!!!");
>   rdtp = this_cpu_ptr(_dynticks);
> - oldval = rdtp->dynticks_nesting;
> - rdtp->dynticks_nesting--;
>

Re: [PATCH 4/4] rcu: Fix dyntick-idle tracing

2017-04-06 Thread Paul E. McKenney

On Thu, Apr 06, 2017 at 12:42:41PM -0400, Steven Rostedt wrote:
> From: "Paul E. McKenney" 
> 
> The tracing subsystem started using rcu_irq_entry() and rcu_irq_exit()
> (with my blessing) to allow the current _rcuidle alternative tracepoint
> name to be dispensed with while still maintaining good performance.
> Unfortunately, this causes RCU's dyntick-idle entry code's tracing to
> appear to RCU like an interrupt that occurs where RCU is not designed
> to handle interrupts.
> 
> This commit fixes this problem by moving the zeroing of ->dynticks_nesting
> after the offending trace_rcu_dyntick() statement, which narrows the
> window of vulnerability to a pair of adjacent statements that are now
> marked with comments to that effect.
> 
> Link: http://lkml.kernel.org/r/20170405193928.gm1...@linux.vnet.ibm.com
> 
> Reported-by: Steven Rostedt 
> Signed-off-by: Paul E. McKenney 
> Signed-off-by: Steven Rostedt (VMware) 

Acked-by: Paul E. McKenney 

Really confirming my Signed-off-by given Steven's changes, but whatever.  ;-)

Thanx, Paul

> ---
>  kernel/rcu/tree.c | 48 +++-
>  1 file changed, 23 insertions(+), 25 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 50fee7689e71..8b4d273331e4 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -57,6 +57,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
> 
>  #include "tree.h"
>  #include "rcu.h"
> @@ -771,25 +772,24 @@ cpu_needs_another_gp(struct rcu_state *rsp, struct 
> rcu_data *rdp)
>  }
> 
>  /*
> - * rcu_eqs_enter_common - current CPU is moving towards extended quiescent 
> state
> + * rcu_eqs_enter_common - current CPU is entering an extended quiescent state
>   *
> - * If the new value of the ->dynticks_nesting counter now is zero,
> - * we really have entered idle, and must do the appropriate accounting.
> - * The caller must have disabled interrupts.
> + * Enter idle, doing appropriate accounting.  The caller must have
> + * disabled interrupts.
>   */
> -static void rcu_eqs_enter_common(long long oldval, bool user)
> +static void rcu_eqs_enter_common(bool user)
>  {
>   struct rcu_state *rsp;
>   struct rcu_data *rdp;
> - RCU_TRACE(struct rcu_dynticks *rdtp = this_cpu_ptr(_dynticks);)
> + struct rcu_dynticks *rdtp = this_cpu_ptr(_dynticks);
> 
> - trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
> + trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);
>   if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
>   !user && !is_idle_task(current)) {
>   struct task_struct *idle __maybe_unused =
>   idle_task(smp_processor_id());
> 
> - trace_rcu_dyntick(TPS("Error on entry: not idle task"), oldval, 
> 0);
> + trace_rcu_dyntick(TPS("Error on entry: not idle task"), 
> rdtp->dynticks_nesting, 0);
>   rcu_ftrace_dump(DUMP_ORIG);
>   WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
> current->pid, current->comm,
> @@ -800,7 +800,10 @@ static void rcu_eqs_enter_common(long long oldval, bool 
> user)
>   do_nocb_deferred_wakeup(rdp);
>   }
>   rcu_prepare_for_idle();
> - rcu_dynticks_eqs_enter();
> + stack_tracer_disable();
> + rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */
> + rcu_dynticks_eqs_enter(); /* After this, tracing works again. */
> + stack_tracer_enable();
>   rcu_dynticks_task_enter();
> 
>   /*
> @@ -821,19 +824,15 @@ static void rcu_eqs_enter_common(long long oldval, bool 
> user)
>   */
>  static void rcu_eqs_enter(bool user)
>  {
> - long long oldval;
>   struct rcu_dynticks *rdtp;
> 
>   rdtp = this_cpu_ptr(_dynticks);
> - oldval = rdtp->dynticks_nesting;
>   WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
> -  (oldval & DYNTICK_TASK_NEST_MASK) == 0);
> - if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) {
> - rdtp->dynticks_nesting = 0;
> - rcu_eqs_enter_common(oldval, user);
> - } else {
> +  (rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
> + if ((rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 
> DYNTICK_TASK_NEST_VALUE)
> + rcu_eqs_enter_common(user);
> + else
>   rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
> - }
>  }
> 
>  /**
> @@ -892,19 +891,18 @@ void rcu_user_enter(void)
>   */
>  void rcu_irq_exit(void)
>  {
> - long long oldval;
>   struct rcu_dynticks *rdtp;
> 
>   RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_exit() invoked with irqs 
> enabled!!!");
>   rdtp = this_cpu_ptr(_dynticks);
> - oldval = rdtp->dynticks_nesting;
> - rdtp->dynticks_nesting--;
>   WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
> -  rdtp->dynticks_nesting < 0);
> - if

[PATCH 4/4] rcu: Fix dyntick-idle tracing

2017-04-06 Thread Steven Rostedt

From: "Paul E. McKenney" 

The tracing subsystem started using rcu_irq_entry() and rcu_irq_exit()
(with my blessing) to allow the current _rcuidle alternative tracepoint
name to be dispensed with while still maintaining good performance.
Unfortunately, this causes RCU's dyntick-idle entry code's tracing to
appear to RCU like an interrupt that occurs where RCU is not designed
to handle interrupts.

This commit fixes this problem by moving the zeroing of ->dynticks_nesting
after the offending trace_rcu_dyntick() statement, which narrows the
window of vulnerability to a pair of adjacent statements that are now
marked with comments to that effect.

Link: http://lkml.kernel.org/r/20170405193928.gm1...@linux.vnet.ibm.com

Reported-by: Steven Rostedt 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Steven Rostedt (VMware) 
---
 kernel/rcu/tree.c | 48 +++-
 1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 50fee7689e71..8b4d273331e4 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -57,6 +57,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include "tree.h"
 #include "rcu.h"
@@ -771,25 +772,24 @@ cpu_needs_another_gp(struct rcu_state *rsp, struct 
rcu_data *rdp)
 }
 
 /*
- * rcu_eqs_enter_common - current CPU is moving towards extended quiescent 
state
+ * rcu_eqs_enter_common - current CPU is entering an extended quiescent state
  *
- * If the new value of the ->dynticks_nesting counter now is zero,
- * we really have entered idle, and must do the appropriate accounting.
- * The caller must have disabled interrupts.
+ * Enter idle, doing appropriate accounting.  The caller must have
+ * disabled interrupts.
  */
-static void rcu_eqs_enter_common(long long oldval, bool user)
+static void rcu_eqs_enter_common(bool user)
 {
struct rcu_state *rsp;
struct rcu_data *rdp;
-   RCU_TRACE(struct rcu_dynticks *rdtp = this_cpu_ptr(_dynticks);)
+   struct rcu_dynticks *rdtp = this_cpu_ptr(_dynticks);
 
-   trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
+   trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!user && !is_idle_task(current)) {
struct task_struct *idle __maybe_unused =
idle_task(smp_processor_id());
 
-   trace_rcu_dyntick(TPS("Error on entry: not idle task"), oldval, 
0);
+   trace_rcu_dyntick(TPS("Error on entry: not idle task"), 
rdtp->dynticks_nesting, 0);
rcu_ftrace_dump(DUMP_ORIG);
WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
  current->pid, current->comm,
@@ -800,7 +800,10 @@ static void rcu_eqs_enter_common(long long oldval, bool 
user)
do_nocb_deferred_wakeup(rdp);
}
rcu_prepare_for_idle();
-   rcu_dynticks_eqs_enter();
+   stack_tracer_disable();
+   rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */
+   rcu_dynticks_eqs_enter(); /* After this, tracing works again. */
+   stack_tracer_enable();
rcu_dynticks_task_enter();
 
/*
@@ -821,19 +824,15 @@ static void rcu_eqs_enter_common(long long oldval, bool 
user)
  */
 static void rcu_eqs_enter(bool user)
 {
-   long long oldval;
struct rcu_dynticks *rdtp;
 
rdtp = this_cpu_ptr(_dynticks);
-   oldval = rdtp->dynticks_nesting;
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-(oldval & DYNTICK_TASK_NEST_MASK) == 0);
-   if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) {
-   rdtp->dynticks_nesting = 0;
-   rcu_eqs_enter_common(oldval, user);
-   } else {
+(rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
+   if ((rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 
DYNTICK_TASK_NEST_VALUE)
+   rcu_eqs_enter_common(user);
+   else
rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
-   }
 }
 
 /**
@@ -892,19 +891,18 @@ void rcu_user_enter(void)
  */
 void rcu_irq_exit(void)
 {
-   long long oldval;
struct rcu_dynticks *rdtp;
 
RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_exit() invoked with irqs 
enabled!!!");
rdtp = this_cpu_ptr(_dynticks);
-   oldval = rdtp->dynticks_nesting;
-   rdtp->dynticks_nesting--;
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-rdtp->dynticks_nesting < 0);
-   if (rdtp->dynticks_nesting)
-   trace_rcu_dyntick(TPS("--="), oldval, rdtp->dynticks_nesting);
-   else
-   rcu_eqs_enter_common(oldval, true);
+rdtp->dynticks_nesting < 1);
+   if (rdtp->dynticks_nesting <= 1) {
+   rcu_eqs_enter_common(true);

[PATCH 4/4] rcu: Fix dyntick-idle tracing

2017-04-06 Thread Steven Rostedt

From: "Paul E. McKenney" 

The tracing subsystem started using rcu_irq_entry() and rcu_irq_exit()
(with my blessing) to allow the current _rcuidle alternative tracepoint
name to be dispensed with while still maintaining good performance.
Unfortunately, this causes RCU's dyntick-idle entry code's tracing to
appear to RCU like an interrupt that occurs where RCU is not designed
to handle interrupts.

This commit fixes this problem by moving the zeroing of ->dynticks_nesting
after the offending trace_rcu_dyntick() statement, which narrows the
window of vulnerability to a pair of adjacent statements that are now
marked with comments to that effect.

Link: http://lkml.kernel.org/r/20170405193928.gm1...@linux.vnet.ibm.com

Reported-by: Steven Rostedt 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Steven Rostedt (VMware) 
---
 kernel/rcu/tree.c | 48 +++-
 1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 50fee7689e71..8b4d273331e4 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -57,6 +57,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include "tree.h"
 #include "rcu.h"
@@ -771,25 +772,24 @@ cpu_needs_another_gp(struct rcu_state *rsp, struct 
rcu_data *rdp)
 }
 
 /*
- * rcu_eqs_enter_common - current CPU is moving towards extended quiescent 
state
+ * rcu_eqs_enter_common - current CPU is entering an extended quiescent state
  *
- * If the new value of the ->dynticks_nesting counter now is zero,
- * we really have entered idle, and must do the appropriate accounting.
- * The caller must have disabled interrupts.
+ * Enter idle, doing appropriate accounting.  The caller must have
+ * disabled interrupts.
  */
-static void rcu_eqs_enter_common(long long oldval, bool user)
+static void rcu_eqs_enter_common(bool user)
 {
struct rcu_state *rsp;
struct rcu_data *rdp;
-   RCU_TRACE(struct rcu_dynticks *rdtp = this_cpu_ptr(_dynticks);)
+   struct rcu_dynticks *rdtp = this_cpu_ptr(_dynticks);
 
-   trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
+   trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!user && !is_idle_task(current)) {
struct task_struct *idle __maybe_unused =
idle_task(smp_processor_id());
 
-   trace_rcu_dyntick(TPS("Error on entry: not idle task"), oldval, 
0);
+   trace_rcu_dyntick(TPS("Error on entry: not idle task"), 
rdtp->dynticks_nesting, 0);
rcu_ftrace_dump(DUMP_ORIG);
WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
  current->pid, current->comm,
@@ -800,7 +800,10 @@ static void rcu_eqs_enter_common(long long oldval, bool 
user)
do_nocb_deferred_wakeup(rdp);
}
rcu_prepare_for_idle();
-   rcu_dynticks_eqs_enter();
+   stack_tracer_disable();
+   rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */
+   rcu_dynticks_eqs_enter(); /* After this, tracing works again. */
+   stack_tracer_enable();
rcu_dynticks_task_enter();
 
/*
@@ -821,19 +824,15 @@ static void rcu_eqs_enter_common(long long oldval, bool 
user)
  */
 static void rcu_eqs_enter(bool user)
 {
-   long long oldval;
struct rcu_dynticks *rdtp;
 
rdtp = this_cpu_ptr(_dynticks);
-   oldval = rdtp->dynticks_nesting;
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-(oldval & DYNTICK_TASK_NEST_MASK) == 0);
-   if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) {
-   rdtp->dynticks_nesting = 0;
-   rcu_eqs_enter_common(oldval, user);
-   } else {
+(rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
+   if ((rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 
DYNTICK_TASK_NEST_VALUE)
+   rcu_eqs_enter_common(user);
+   else
rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
-   }
 }
 
 /**
@@ -892,19 +891,18 @@ void rcu_user_enter(void)
  */
 void rcu_irq_exit(void)
 {
-   long long oldval;
struct rcu_dynticks *rdtp;
 
RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_exit() invoked with irqs 
enabled!!!");
rdtp = this_cpu_ptr(_dynticks);
-   oldval = rdtp->dynticks_nesting;
-   rdtp->dynticks_nesting--;
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-rdtp->dynticks_nesting < 0);
-   if (rdtp->dynticks_nesting)
-   trace_rcu_dyntick(TPS("--="), oldval, rdtp->dynticks_nesting);
-   else
-   rcu_eqs_enter_common(oldval, true);
+rdtp->dynticks_nesting < 1);
+   if (rdtp->dynticks_nesting <= 1) {
+   rcu_eqs_enter_common(true);
+   } else {
+   trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nesting,

Re: [PATCH 4/4] rcu: Fix dyntick-idle tracing

Re: [PATCH 4/4] rcu: Fix dyntick-idle tracing

Re: [PATCH 4/4] rcu: Fix dyntick-idle tracing

Re: [PATCH 4/4] rcu: Fix dyntick-idle tracing

[PATCH 4/4] rcu: Fix dyntick-idle tracing

[PATCH 4/4] rcu: Fix dyntick-idle tracing

6 matches

Site Navigation

Mail list logo

Footer information