From: Thomas Gleixner <tglx@linutronix.de>
To: Nitesh Lal <nilal@redhat.com>,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
Robin Murphy <robin.murphy@arm.com>,
Marcelo Tosatti <mtosatti@redhat.com>
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>,
Alex Belits <abelits@marvell.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,
Marc Zyngier <maz@kernel.org>,
Neil Horman <nhorman@tuxdriver.com>,
pjwaskiewicz@gmail.com
Subject: [PATCH] genirq: Provide new interfaces for affinity hints
Date: Fri, 21 May 2021 14:03:06 +0200 [thread overview]
Message-ID: <87wnrs9tvp.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <87zgwo9u79.ffs@nanos.tec.linutronix.de>
The discussion about removing the side effect of irq_set_affinity_hint() of
actually applying the cpumask (if not NULL) as affinity to the interrupt,
unearthed a few unpleasantries:
1) The modular perf drivers rely on the current behaviour for the very
wrong reasons.
2) While none of the other drivers prevents user space from changing
the affinity, a cursorily inspection shows that there are at least
expectations in some drivers.
#1 needs to be cleaned up anyway, so that's not a problem
#2 might result in subtle regressions especially when irqbalanced (which
nowadays ignores the affinity hint) is disabled.
Provide new interfaces:
irq_update_affinity_hint() - Only sets the affinity hint pointer
irq_apply_affinity_hint() - Set the pointer and apply the affinity to
the interrupt
Make irq_set_affinity_hint() a wrapper around irq_apply_affinity_hint() and
document it to be phased out.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210501021832.743094-1-jesse.brandeburg@intel.com
---
Applies on:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq/core
---
include/linux/interrupt.h | 41 ++++++++++++++++++++++++++++++++++++++++-
kernel/irq/manage.c | 8 ++++----
2 files changed, 44 insertions(+), 5 deletions(-)
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -328,7 +328,46 @@ extern int irq_force_affinity(unsigned i
extern int irq_can_set_affinity(unsigned int irq);
extern int irq_select_affinity(unsigned int irq);
-extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
+extern int __irq_apply_affinity_hint(unsigned int irq, const struct cpumask *m,
+ bool setaffinity);
+
+/**
+ * irq_update_affinity_hint - Update the affinity hint
+ * @irq: Interrupt to update
+ * @cpumask: cpumask pointer (NULL to clear the hint)
+ *
+ * Updates the affinity hint, but does not change the affinity of the interrupt.
+ */
+static inline int
+irq_update_affinity_hint(unsigned int irq, const struct cpumask *m)
+{
+ return __irq_apply_affinity_hint(irq, m, true);
+}
+
+/**
+ * irq_apply_affinity_hint - Update the affinity hint and apply the provided
+ * cpumask to the interrupt
+ * @irq: Interrupt to update
+ * @cpumask: cpumask pointer (NULL to clear the hint)
+ *
+ * Updates the affinity hint and if @cpumask is not NULL it applies it as
+ * the affinity of that interrupt.
+ */
+static inline int
+irq_apply_affinity_hint(unsigned int irq, const struct cpumask *m)
+{
+ return __irq_apply_affinity_hint(irq, m, true);
+}
+
+/*
+ * Deprecated. Use irq_update_affinity_hint() or irq_apply_affinity_hint()
+ * instead.
+ */
+static inline int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
+{
+ return irq_apply_affinity_hint(irq, cpumask);
+}
+
extern int irq_update_affinity_desc(unsigned int irq,
struct irq_affinity_desc *affinity);
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -487,7 +487,8 @@ int irq_force_affinity(unsigned int irq,
}
EXPORT_SYMBOL_GPL(irq_force_affinity);
-int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
+int __irq_apply_affinity_hint(unsigned int irq, const struct cpumask *m,
+ bool setaffinity)
{
unsigned long flags;
struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
@@ -496,12 +497,11 @@ int irq_set_affinity_hint(unsigned int i
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)
+ if (m && setaffinity)
__irq_set_affinity(irq, m, false);
return 0;
}
-EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
+EXPORT_SYMBOL_GPL(__irq_apply_affinity_hint);
static void irq_affinity_notify(struct work_struct *work)
{
next prev parent reply other threads:[~2021-05-21 12:03 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-01 2:18 [PATCH tip:irq/core v1] genirq: remove auto-set of the mask when setting the hint Jesse Brandeburg
2021-05-04 12:15 ` 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 ` Thomas Gleixner [this message]
2021-05-21 15:45 ` [PATCH] genirq: Provide new interfaces for affinity hints 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
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