Re: [PATCH tip/core/rcu 6/8] rcutorture: Print symbolic name for ->gp_state
On Sat, Dec 05, 2015 at 05:54:36PM -0800, Paul E. McKenney wrote:
> On Fri, Dec 04, 2015 at 05:04:21PM -0800, Josh Triplett wrote:
> > On Fri, Dec 04, 2015 at 04:23:50PM -0800, Paul E. McKenney wrote:
> > > Currently, ->gp_state is printed as an integer, which slows debugging.
> > > This commit therefore prints a symbolic name in addition to the integer.
> > >
> > > Signed-off-by: Paul E. McKenney
> > > [ Updated to fix relational operator called out by Dan Carpenter. ]
> > > ---
> > > kernel/rcu/tree.c | 15 +--
> > > kernel/rcu/tree.h | 9 +
> > > 2 files changed, 22 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > > index 7b78c88e19a3..491c99a73996 100644
> > > --- a/kernel/rcu/tree.c
> > > +++ b/kernel/rcu/tree.c
> > > @@ -1187,6 +1187,16 @@ static void record_gp_stall_check_time(struct
> > > rcu_state *rsp)
> > > }
> > >
> > > /*
> > > + * Convert a ->gp_state value to a character string.
> > > + */
> > > +static char *gp_state_getname(short gs)
> >
> > Same comment about "const char *"
>
> Good point, fixed!
>
> > > +{
> > > + if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
> > > + return "???";
> > > + return gp_state_names[gs];
> > > +}
> > > +
> > > +/*
> > > * Complain about starvation of grace-period kthread.
> > > */
> > > static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
> > > @@ -1197,10 +1207,11 @@ static void
> > > rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
> > > j = jiffies;
> > > gpa = READ_ONCE(rsp->gp_activity);
> > > if (j - gpa > 2 * HZ) {
> > > - pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d
> > > ->state=%#lx\n",
> > > + pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x
> > > %s(%d) ->state=%#lx\n",
> > > rsp->name, j - gpa,
> > > rsp->gpnum, rsp->completed,
> > > -rsp->gp_flags, rsp->gp_state,
> > > +rsp->gp_flags,
> > > +gp_state_getname(rsp->gp_state), rsp->gp_state,
> > > rsp->gp_kthread ? rsp->gp_kthread->state : ~0);
> > > if (rsp->gp_kthread)
> > > sched_show_task(rsp->gp_kthread);
> > > diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
> > > index f32bebb6bc90..f0304988e3f8 100644
> > > --- a/kernel/rcu/tree.h
> > > +++ b/kernel/rcu/tree.h
> > > @@ -544,6 +544,15 @@ struct rcu_state {
> > > #define RCU_GP_DOING_FQS 4 /* Wait done for force-quiescent-state
> > > time. */
> > > #define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */
> > > #define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */
> > > +static char * const gp_state_names[] = {
> >
> > Same comment about "const char * const", but also, should this really go
> > in a header file? Do any circumstances exist where this header could
> > get included in more than one source file in a given build? If so,
> > multiple copies of this array could potentially end up in the binary, if
> > the compiler fails to merge them.
>
> I added the const.
>
> However, I left the array in the .h file. The issue is that the #defines
> really have to be in the tree.h file. Given that, if I move the array
> elsewhere, they will very likely drift out of sync. So this sounds like
> a job for the compiler/linker...
>
> Ah, but there is another approach. It turns out that tree.h in included
> only from tree.c and tree_trace.c. And tree_trace.c defines a CPP symbol
> RCU_TREE_NONCORE that is used elsewhere in tree.h to keep tree_trace.c's
> mitts off a number of attractive but dangerous functions. So I just put
> the array under "#ifndef RCU_TREE_NONCORE".
>
> Fair enough?
Fair enough.
Reviewed-by: Josh Triplett
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Re: [PATCH tip/core/rcu 6/8] rcutorture: Print symbolic name for ->gp_state
On Fri, Dec 04, 2015 at 05:04:21PM -0800, Josh Triplett wrote:
> On Fri, Dec 04, 2015 at 04:23:50PM -0800, Paul E. McKenney wrote:
> > Currently, ->gp_state is printed as an integer, which slows debugging.
> > This commit therefore prints a symbolic name in addition to the integer.
> >
> > Signed-off-by: Paul E. McKenney
> > [ Updated to fix relational operator called out by Dan Carpenter. ]
> > ---
> > kernel/rcu/tree.c | 15 +--
> > kernel/rcu/tree.h | 9 +
> > 2 files changed, 22 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 7b78c88e19a3..491c99a73996 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -1187,6 +1187,16 @@ static void record_gp_stall_check_time(struct
> > rcu_state *rsp)
> > }
> >
> > /*
> > + * Convert a ->gp_state value to a character string.
> > + */
> > +static char *gp_state_getname(short gs)
>
> Same comment about "const char *"
Good point, fixed!
> > +{
> > + if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
> > + return "???";
> > + return gp_state_names[gs];
> > +}
> > +
> > +/*
> > * Complain about starvation of grace-period kthread.
> > */
> > static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
> > @@ -1197,10 +1207,11 @@ static void rcu_check_gp_kthread_starvation(struct
> > rcu_state *rsp)
> > j = jiffies;
> > gpa = READ_ONCE(rsp->gp_activity);
> > if (j - gpa > 2 * HZ) {
> > - pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d
> > ->state=%#lx\n",
> > + pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x
> > %s(%d) ->state=%#lx\n",
> >rsp->name, j - gpa,
> >rsp->gpnum, rsp->completed,
> > - rsp->gp_flags, rsp->gp_state,
> > + rsp->gp_flags,
> > + gp_state_getname(rsp->gp_state), rsp->gp_state,
> >rsp->gp_kthread ? rsp->gp_kthread->state : ~0);
> > if (rsp->gp_kthread)
> > sched_show_task(rsp->gp_kthread);
> > diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
> > index f32bebb6bc90..f0304988e3f8 100644
> > --- a/kernel/rcu/tree.h
> > +++ b/kernel/rcu/tree.h
> > @@ -544,6 +544,15 @@ struct rcu_state {
> > #define RCU_GP_DOING_FQS 4 /* Wait done for force-quiescent-state time. */
> > #define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */
> > #define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */
> > +static char * const gp_state_names[] = {
>
> Same comment about "const char * const", but also, should this really go
> in a header file? Do any circumstances exist where this header could
> get included in more than one source file in a given build? If so,
> multiple copies of this array could potentially end up in the binary, if
> the compiler fails to merge them.
I added the const.
However, I left the array in the .h file. The issue is that the #defines
really have to be in the tree.h file. Given that, if I move the array
elsewhere, they will very likely drift out of sync. So this sounds like
a job for the compiler/linker...
Ah, but there is another approach. It turns out that tree.h in included
only from tree.c and tree_trace.c. And tree_trace.c defines a CPP symbol
RCU_TREE_NONCORE that is used elsewhere in tree.h to keep tree_trace.c's
mitts off a number of attractive but dangerous functions. So I just put
the array under "#ifndef RCU_TREE_NONCORE".
Fair enough?
Thanx, Paul
> > + "RCU_GP_IDLE",
> > + "RCU_GP_WAIT_GPS",
> > + "RCU_GP_DONE_GPS",
> > + "RCU_GP_WAIT_FQS",
> > + "RCU_GP_DOING_FQS",
> > + "RCU_GP_CLEANUP",
> > + "RCU_GP_CLEANED",
> > +};
> >
> > extern struct list_head rcu_struct_flavors;
> >
> > --
> > 2.5.2
> >
>
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Re: [PATCH tip/core/rcu 6/8] rcutorture: Print symbolic name for ->gp_state
On Fri, Dec 04, 2015 at 04:23:50PM -0800, Paul E. McKenney wrote:
> Currently, ->gp_state is printed as an integer, which slows debugging.
> This commit therefore prints a symbolic name in addition to the integer.
>
> Signed-off-by: Paul E. McKenney
> [ Updated to fix relational operator called out by Dan Carpenter. ]
> ---
> kernel/rcu/tree.c | 15 +--
> kernel/rcu/tree.h | 9 +
> 2 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 7b78c88e19a3..491c99a73996 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1187,6 +1187,16 @@ static void record_gp_stall_check_time(struct
> rcu_state *rsp)
> }
>
> /*
> + * Convert a ->gp_state value to a character string.
> + */
> +static char *gp_state_getname(short gs)
Same comment about "const char *"
> +{
> + if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
> + return "???";
> + return gp_state_names[gs];
> +}
> +
> +/*
> * Complain about starvation of grace-period kthread.
> */
> static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
> @@ -1197,10 +1207,11 @@ static void rcu_check_gp_kthread_starvation(struct
> rcu_state *rsp)
> j = jiffies;
> gpa = READ_ONCE(rsp->gp_activity);
> if (j - gpa > 2 * HZ) {
> - pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d
> ->state=%#lx\n",
> + pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x
> %s(%d) ->state=%#lx\n",
> rsp->name, j - gpa,
> rsp->gpnum, rsp->completed,
> -rsp->gp_flags, rsp->gp_state,
> +rsp->gp_flags,
> +gp_state_getname(rsp->gp_state), rsp->gp_state,
> rsp->gp_kthread ? rsp->gp_kthread->state : ~0);
> if (rsp->gp_kthread)
> sched_show_task(rsp->gp_kthread);
> diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
> index f32bebb6bc90..f0304988e3f8 100644
> --- a/kernel/rcu/tree.h
> +++ b/kernel/rcu/tree.h
> @@ -544,6 +544,15 @@ struct rcu_state {
> #define RCU_GP_DOING_FQS 4 /* Wait done for force-quiescent-state time. */
> #define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */
> #define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */
> +static char * const gp_state_names[] = {
Same comment about "const char * const", but also, should this really go
in a header file? Do any circumstances exist where this header could
get included in more than one source file in a given build? If so,
multiple copies of this array could potentially end up in the binary, if
the compiler fails to merge them.
> + "RCU_GP_IDLE",
> + "RCU_GP_WAIT_GPS",
> + "RCU_GP_DONE_GPS",
> + "RCU_GP_WAIT_FQS",
> + "RCU_GP_DOING_FQS",
> + "RCU_GP_CLEANUP",
> + "RCU_GP_CLEANED",
> +};
>
> extern struct list_head rcu_struct_flavors;
>
> --
> 2.5.2
>
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