* [PATCH] rcu/nocb: Fix dump_tree hierarchy print always active
@ 2019-10-04 19:49 Stefan Reiter
2019-10-04 22:24 ` Paul E. McKenney
0 siblings, 1 reply; 4+ messages in thread
From: Stefan Reiter @ 2019-10-04 19:49 UTC (permalink / raw)
To: rcu
Cc: Stefan Reiter, Paul E. McKenney, Josh Triplett, Steven Rostedt,
Mathieu Desnoyers, Lai Jiangshan, Joel Fernandes, linux-kernel
Commit 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if
dump_tree") added print statements to rcu_organize_nocb_kthreads for
debugging, but incorrectly guarded them, causing the function to always
spew out its message.
This patch fixes it by guarding both pr_alert statements with dump_tree,
while also changing the second pr_alert to a pr_cont, to print the
hierarchy in a single line (assuming that's how it was supposed to
work).
Fixes: 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if dump_tree")
Signed-off-by: Stefan Reiter <stefan@pimaker.at>
---
First time contributing to the kernel, hope I'm doing this right :)
kernel/rcu/tree_plugin.h | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 2defc7fe74c3..7cbf4a0f3eff 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2346,15 +2346,19 @@ static void __init rcu_organize_nocb_kthreads(void)
nl = DIV_ROUND_UP(rdp->cpu + 1, ls) * ls;
rdp->nocb_gp_rdp = rdp;
rdp_gp = rdp;
- if (!firsttime && dump_tree)
- pr_cont("\n");
- firsttime = false;
- pr_alert("%s: No-CB GP kthread CPU %d:", __func__, cpu);
+ if (dump_tree) {
+ if (!firsttime)
+ pr_cont("\n");
+ firsttime = false;
+ pr_alert("%s: No-CB GP kthread CPU %d:",
+ __func__, cpu);
+ }
} else {
/* Another CB kthread, link to previous GP kthread. */
rdp->nocb_gp_rdp = rdp_gp;
rdp_prev->nocb_next_cb_rdp = rdp;
- pr_alert(" %d", cpu);
+ if (dump_tree)
+ pr_cont(" %d", cpu);
}
rdp_prev = rdp;
}
--
2.23.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] rcu/nocb: Fix dump_tree hierarchy print always active 2019-10-04 19:49 [PATCH] rcu/nocb: Fix dump_tree hierarchy print always active Stefan Reiter @ 2019-10-04 22:24 ` Paul E. McKenney 2019-10-07 1:26 ` Paul E. McKenney 0 siblings, 1 reply; 4+ messages in thread From: Paul E. McKenney @ 2019-10-04 22:24 UTC (permalink / raw) To: Stefan Reiter Cc: rcu, Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Joel Fernandes, linux-kernel On Fri, Oct 04, 2019 at 07:49:10PM +0000, Stefan Reiter wrote: > Commit 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if > dump_tree") added print statements to rcu_organize_nocb_kthreads for > debugging, but incorrectly guarded them, causing the function to always > spew out its message. > > This patch fixes it by guarding both pr_alert statements with dump_tree, > while also changing the second pr_alert to a pr_cont, to print the > hierarchy in a single line (assuming that's how it was supposed to > work). > > Fixes: 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if dump_tree") > Signed-off-by: Stefan Reiter <stefan@pimaker.at> Queued for testing and review, thank you! > --- > > First time contributing to the kernel, hope I'm doing this right :) Looks good so far. Then again, I just kicked off the tests. ;-) Thanx, Paul > kernel/rcu/tree_plugin.h | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 2defc7fe74c3..7cbf4a0f3eff 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -2346,15 +2346,19 @@ static void __init rcu_organize_nocb_kthreads(void) > nl = DIV_ROUND_UP(rdp->cpu + 1, ls) * ls; > rdp->nocb_gp_rdp = rdp; > rdp_gp = rdp; > - if (!firsttime && dump_tree) > - pr_cont("\n"); > - firsttime = false; > - pr_alert("%s: No-CB GP kthread CPU %d:", __func__, cpu); > + if (dump_tree) { > + if (!firsttime) > + pr_cont("\n"); > + firsttime = false; > + pr_alert("%s: No-CB GP kthread CPU %d:", > + __func__, cpu); > + } > } else { > /* Another CB kthread, link to previous GP kthread. */ > rdp->nocb_gp_rdp = rdp_gp; > rdp_prev->nocb_next_cb_rdp = rdp; > - pr_alert(" %d", cpu); > + if (dump_tree) > + pr_cont(" %d", cpu); > } > rdp_prev = rdp; > } > -- > 2.23.0 > > ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rcu/nocb: Fix dump_tree hierarchy print always active 2019-10-04 22:24 ` Paul E. McKenney @ 2019-10-07 1:26 ` Paul E. McKenney 2019-10-07 17:56 ` Stefan 0 siblings, 1 reply; 4+ messages in thread From: Paul E. McKenney @ 2019-10-07 1:26 UTC (permalink / raw) To: Stefan Reiter Cc: rcu, Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Joel Fernandes, linux-kernel On Fri, Oct 04, 2019 at 03:24:02PM -0700, Paul E. McKenney wrote: > On Fri, Oct 04, 2019 at 07:49:10PM +0000, Stefan Reiter wrote: > > Commit 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if > > dump_tree") added print statements to rcu_organize_nocb_kthreads for > > debugging, but incorrectly guarded them, causing the function to always > > spew out its message. > > > > This patch fixes it by guarding both pr_alert statements with dump_tree, > > while also changing the second pr_alert to a pr_cont, to print the > > hierarchy in a single line (assuming that's how it was supposed to > > work). > > > > Fixes: 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if dump_tree") > > Signed-off-by: Stefan Reiter <stefan@pimaker.at> > > Queued for testing and review, thank you! And here is an updated version to make the special case of a nocb GP kthread having no other nocb CB kthreads look less strange. Does this work for you? Thanx, Paul ------------------------------------------------------------------------ commit e6223b0705369750990c32ddc80251942e61be30 Author: Stefan Reiter <stefan@pimaker.at> Date: Fri Oct 4 19:49:10 2019 +0000 rcu/nocb: Fix dump_tree hierarchy print always active Commit 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if dump_tree") added print statements to rcu_organize_nocb_kthreads for debugging, but incorrectly guarded them, causing the function to always spew out its message. This patch fixes it by guarding both pr_alert statements with dump_tree, while also changing the second pr_alert to a pr_cont, to print the hierarchy in a single line (assuming that's how it was supposed to work). Fixes: 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if dump_tree") Signed-off-by: Stefan Reiter <stefan@pimaker.at> [ paulmck: Make single-nocbs-CPU GP kthreads look less erroneous. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index d5334e4..d43f4e0 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2295,6 +2295,8 @@ static void __init rcu_organize_nocb_kthreads(void) { int cpu; bool firsttime = true; + bool gotnocbs = false; + bool gotnocbscbs = true; int ls = rcu_nocb_gp_stride; int nl = 0; /* Next GP kthread. */ struct rcu_data *rdp; @@ -2317,21 +2319,31 @@ static void __init rcu_organize_nocb_kthreads(void) rdp = per_cpu_ptr(&rcu_data, cpu); if (rdp->cpu >= nl) { /* New GP kthread, set up for CBs & next GP. */ + gotnocbs = true; nl = DIV_ROUND_UP(rdp->cpu + 1, ls) * ls; rdp->nocb_gp_rdp = rdp; rdp_gp = rdp; - if (!firsttime && dump_tree) - pr_cont("\n"); - firsttime = false; - pr_alert("%s: No-CB GP kthread CPU %d:", __func__, cpu); + if (dump_tree) { + if (!firsttime) + pr_cont("%s\n", gotnocbscbs + ? "" : " (self only)"); + gotnocbscbs = false; + firsttime = false; + pr_alert("%s: No-CB GP kthread CPU %d:", + __func__, cpu); + } } else { /* Another CB kthread, link to previous GP kthread. */ + gotnocbscbs = true; rdp->nocb_gp_rdp = rdp_gp; rdp_prev->nocb_next_cb_rdp = rdp; - pr_alert(" %d", cpu); + if (dump_tree) + pr_cont(" %d", cpu); } rdp_prev = rdp; } + if (gotnocbs && dump_tree) + pr_cont("%s\n", gotnocbscbs ? "" : " (self only)"); } /* ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] rcu/nocb: Fix dump_tree hierarchy print always active 2019-10-07 1:26 ` Paul E. McKenney @ 2019-10-07 17:56 ` Stefan 0 siblings, 0 replies; 4+ messages in thread From: Stefan @ 2019-10-07 17:56 UTC (permalink / raw) To: paulmck Cc: rcu, Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Joel Fernandes, linux-kernel On 07/10/2019 03:26, Paul E. McKenney wrote: > > On Fri, Oct 04, 2019 at 03:24:02PM -0700, Paul E. McKenney wrote: >> On Fri, Oct 04, 2019 at 07:49:10PM +0000, Stefan Reiter wrote: >>> Commit 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if >>> dump_tree") added print statements to rcu_organize_nocb_kthreads for >>> debugging, but incorrectly guarded them, causing the function to always >>> spew out its message. >>> >>> This patch fixes it by guarding both pr_alert statements with dump_tree, >>> while also changing the second pr_alert to a pr_cont, to print the >>> hierarchy in a single line (assuming that's how it was supposed to >>> work). >>> >>> Fixes: 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if dump_tree") >>> Signed-off-by: Stefan Reiter <stefan@pimaker.at> >> >> Queued for testing and review, thank you! > > And here is an updated version to make the special case of a nocb GP > kthread having no other nocb CB kthreads look less strange. Does this > work for you? Tested just now, works for me. Thanks for the additional fix! > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit e6223b0705369750990c32ddc80251942e61be30 > Author: Stefan Reiter <stefan@pimaker.at> > Date: Fri Oct 4 19:49:10 2019 +0000 > > rcu/nocb: Fix dump_tree hierarchy print always active > > Commit 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if > dump_tree") added print statements to rcu_organize_nocb_kthreads for > debugging, but incorrectly guarded them, causing the function to always > spew out its message. > > This patch fixes it by guarding both pr_alert statements with dump_tree, > while also changing the second pr_alert to a pr_cont, to print the > hierarchy in a single line (assuming that's how it was supposed to > work). > > Fixes: 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if dump_tree") > Signed-off-by: Stefan Reiter <stefan@pimaker.at> > [ paulmck: Make single-nocbs-CPU GP kthreads look less erroneous. ] > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index d5334e4..d43f4e0 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -2295,6 +2295,8 @@ static void __init rcu_organize_nocb_kthreads(void) > { > int cpu; > bool firsttime = true; > + bool gotnocbs = false; > + bool gotnocbscbs = true; > int ls = rcu_nocb_gp_stride; > int nl = 0; /* Next GP kthread. */ > struct rcu_data *rdp; > @@ -2317,21 +2319,31 @@ static void __init rcu_organize_nocb_kthreads(void) > rdp = per_cpu_ptr(&rcu_data, cpu); > if (rdp->cpu >= nl) { > /* New GP kthread, set up for CBs & next GP. */ > + gotnocbs = true; > nl = DIV_ROUND_UP(rdp->cpu + 1, ls) * ls; > rdp->nocb_gp_rdp = rdp; > rdp_gp = rdp; > - if (!firsttime && dump_tree) > - pr_cont("\n"); > - firsttime = false; > - pr_alert("%s: No-CB GP kthread CPU %d:", __func__, cpu); > + if (dump_tree) { > + if (!firsttime) > + pr_cont("%s\n", gotnocbscbs > + ? "" : " (self only)"); > + gotnocbscbs = false; > + firsttime = false; > + pr_alert("%s: No-CB GP kthread CPU %d:", > + __func__, cpu); > + } > } else { > /* Another CB kthread, link to previous GP kthread. */ > + gotnocbscbs = true; > rdp->nocb_gp_rdp = rdp_gp; > rdp_prev->nocb_next_cb_rdp = rdp; > - pr_alert(" %d", cpu); > + if (dump_tree) > + pr_cont(" %d", cpu); > } > rdp_prev = rdp; > } > + if (gotnocbs && dump_tree) > + pr_cont("%s\n", gotnocbscbs ? "" : " (self only)"); > } > > /* > ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-10-07 17:56 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-10-04 19:49 [PATCH] rcu/nocb: Fix dump_tree hierarchy print always active Stefan Reiter 2019-10-04 22:24 ` Paul E. McKenney 2019-10-07 1:26 ` Paul E. McKenney 2019-10-07 17:56 ` Stefan
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