From: Jesse Brandeburg <jesse.brandeburg@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
jbrandeb@kernel.org, "frederic@kernel.org" <frederic@kernel.org>,
"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
abelits@marvell.com, Robin Murphy <robin.murphy@arm.com>,
"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"sfr@canb.auug.org.au" <sfr@canb.auug.org.au>,
"stephen@networkplumber.org" <stephen@networkplumber.org>,
"rppt@linux.vnet.ibm.com" <rppt@linux.vnet.ibm.com>,
"jinyuqi@huawei.com" <jinyuqi@huawei.com>,
"zhangshaokun@hisilicon.com" <zhangshaokun@hisilicon.com>,
netdev@vger.kernel.org, chris.friesen@windriver.com,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
Nitesh Lal <nilal@redhat.com>
Subject: [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint
Date: Fri, 30 Apr 2021 19:18:32 -0700 [thread overview]
Message-ID: <20210501021832.743094-1-jesse.brandeburg@intel.com> (raw)
It was pointed out by Nitesh that the original work I did in 2014
to automatically set the interrupt affinity when requesting a
mask is no longer necessary. The kernel has moved on and no
longer has the original problem, BUT the original patch
introduced a subtle bug when booting a system with reserved or
excluded CPUs. Drivers calling this function with a mask value
that included a CPU that was currently or in the future
unavailable would generally not update the hint.
I'm sure there are a million ways to solve this, but the simplest
one is to just remove a little code that tries to force the
affinity, as Nitesh has shown it fixes the bug and doesn't seem
to introduce immediate side effects.
While I'm here, introduce a kernel-doc for the hint function.
Ref: https://lore.kernel.org/lkml/CAFki+L=_dd+JgAR12_eBPX0kZO2_6=1dGdgkwHE=u=K6chMeLQ@mail.gmail.com/
Cc: netdev@vger.kernel.org
Fixes: 4fe7ffb7e17c ("genirq: Fix null pointer reference in irq_set_affinity_hint()")
Fixes: e2e64a932556 ("genirq: Set initial affinity in irq_set_affinity_hint()")
Reported-by: Nitesh Lal <nilal@redhat.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
---
!!! NOTE: Compile tested only, would appreciate feedback
---
kernel/irq/manage.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index e976c4927b25..a31df64662d5 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -456,6 +456,16 @@ int __irq_set_affinity(unsigned int irq, const struct cpumask *mask, bool force)
return ret;
}
+/**
+ * irq_set_affinity_hint - set the hint for an irq
+ * @irq: Interrupt for which to set the hint
+ * @m: Mask to indicate which CPUs to suggest for the interrupt, use
+ * NULL here to indicate to clear the value.
+ *
+ * Use this function to recommend which CPU should handle the
+ * interrupt to any userspace that uses /proc/irq/nn/smp_affinity_hint
+ * in order to align interrupts. Pass NULL as the mask to clear the hint.
+ */
int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
{
unsigned long flags;
@@ -465,9 +475,6 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
return -EINVAL;
desc->affinity_hint = m;
irq_put_desc_unlock(desc, flags);
- /* set the initial affinity to prevent every interrupt being on CPU0 */
- if (m)
- __irq_set_affinity(irq, m, false);
return 0;
}
EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
base-commit: 765822e1569a37aab5e69736c52d4ad4a289eba6
--
2.30.2
next reply other threads:[~2021-05-01 2:18 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-01 2:18 Jesse Brandeburg [this message]
2021-05-04 12:15 ` [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint Robin Murphy
2021-05-04 14:29 ` Nitesh Lal
2021-05-04 16:23 ` Jesse Brandeburg
2021-05-17 16:57 ` Nitesh Lal
2021-05-17 17:26 ` Robin Murphy
2021-05-17 18:08 ` Thomas Gleixner
2021-05-17 18:50 ` Robin Murphy
2021-05-17 19:08 ` Thomas Gleixner
2021-05-17 19:43 ` Thomas Gleixner
2021-05-17 20:18 ` Thomas Gleixner
2021-05-17 18:21 ` Nitesh Lal
2021-05-17 19:47 ` Thomas Gleixner
2021-05-17 21:13 ` Nitesh Lal
2021-05-17 20:48 ` Thomas Gleixner
2021-05-17 22:44 ` Nitesh Lal
2021-05-18 0:03 ` Thomas Gleixner
2021-05-18 0:23 ` Nitesh Lal
2021-05-20 21:57 ` Nitesh Lal
2021-05-21 0:03 ` Nitesh Lal
2021-05-21 11:56 ` Thomas Gleixner
2021-05-21 12:03 ` [PATCH] genirq: Provide new interfaces for affinity hints Thomas Gleixner
2021-05-21 15:45 ` Lijun Pan
2021-05-21 21:45 ` Thomas Gleixner
2021-05-21 16:13 ` Nitesh Lal
2021-05-21 21:48 ` Thomas Gleixner
2021-06-04 20:35 ` Nitesh Lal
2021-05-27 10:03 ` Shung-Hsi Yu
2021-05-27 10:21 ` Shung-Hsi Yu
2021-05-27 13:06 ` Nitesh Lal
2021-05-28 7:20 ` Shung-Hsi Yu
2021-06-07 17:00 ` Nitesh Lal
2021-06-14 16:12 ` Nitesh Lal
2021-05-21 13:46 ` [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint Nitesh Lal
2021-05-21 15:15 ` Thomas Gleixner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210501021832.743094-1-jesse.brandeburg@intel.com \
--to=jesse.brandeburg@intel.com \
--cc=abelits@marvell.com \
--cc=akpm@linux-foundation.org \
--cc=bhelgaas@google.com \
--cc=chris.friesen@windriver.com \
--cc=davem@davemloft.net \
--cc=frederic@kernel.org \
--cc=intel-wired-lan@lists.osuosl.org \
--cc=jbrandeb@kernel.org \
--cc=jinyuqi@huawei.com \
--cc=juri.lelli@redhat.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=mtosatti@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=nilal@redhat.com \
--cc=peterz@infradead.org \
--cc=robin.murphy@arm.com \
--cc=rostedt@goodmis.org \
--cc=rppt@linux.vnet.ibm.com \
--cc=sfr@canb.auug.org.au \
--cc=stephen@networkplumber.org \
--cc=tglx@linutronix.de \
--cc=zhangshaokun@hisilicon.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).