2018-05-11 08:10:55

by Dou Liyang

Subject: [PATCH] x86/vector: Merge the allocate_vector() into assign_vector_locked()

The assign_vector_locked() calls allocate_vector to get a real vector for
an IRQ. If the current target CPU is online and in the new requested
affinity mask, allocate_vector() will return 0 and nothing should be done.

But, the assign_vector_locked() always call the apic_update_irq_cfg(). it's
pointless.

Merge the two function to avoid this situation and make the code simplify.

Signed-off-by: Dou Liyang <[email protected]>
---
arch/x86/kernel/apic/vector.c | 17 ++++-------------
1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index bb6f7a2148d7..a75de0792942 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -218,7 +218,8 @@ static int reserve_irq_vector(struct irq_data *irqd)
return 0;
}

-static int allocate_vector(struct irq_data *irqd, const struct cpumask *dest)
+static int
+assign_vector_locked(struct irq_data *irqd, const struct cpumask *dest)
{
struct apic_chip_data *apicd = apic_chip_data(irqd);
bool resvd = apicd->has_reserved;
@@ -236,22 +237,12 @@ static int allocate_vector(struct irq_data *irqd, const struct cpumask *dest)
return 0;

vector = irq_matrix_alloc(vector_matrix, dest, resvd, &cpu);
- if (vector > 0)
- apic_update_vector(irqd, vector, cpu);
trace_vector_alloc(irqd->irq, vector, resvd, vector);
- return vector;
-}
-
-static int assign_vector_locked(struct irq_data *irqd,
- const struct cpumask *dest)
-{
- struct apic_chip_data *apicd = apic_chip_data(irqd);
- int vector = allocate_vector(irqd, dest);
-
if (vector < 0)
return vector;
+ apic_update_vector(irqd, vector, cpu);
+ apic_update_irq_cfg(irqd, vector, cpu);

- apic_update_irq_cfg(irqd, apicd->vector, apicd->cpu);
return 0;
}

--
2.14.3

2018-05-19 13:14:10

by tip-bot for Vasyl Gomonovych

Subject: [tip:x86/apic] x86/vector: Merge allocate_vector() into assign_vector_locked()

Commit-ID: 2773397171ac4b6e794ba0b3e34c06cbaf29897a
Gitweb: https://git.kernel.org/tip/2773397171ac4b6e794ba0b3e34c06cbaf29897a
Author: Dou Liyang <[email protected]>
AuthorDate: Fri, 11 May 2018 16:09:56 +0800
Committer: Thomas Gleixner <[email protected]>
CommitDate: Sat, 19 May 2018 15:09:11 +0200

x86/vector: Merge allocate_vector() into assign_vector_locked()

assign_vector_locked() calls allocate_vector() to get a real vector for an
IRQ. If the current target CPU is online and in the new requested affinity
mask, allocate_vector() will return 0 and nothing should be done. But,
assign_vector_locked() calls apic_update_irq_cfg() even in that case which
is pointless.

allocate_vector() is not called from anything else, so the functions can be
merged and in case of no change the apic_update_irq_cfg() can be avoided.

[ tglx: Massaged changelog ]

Signed-off-by: Dou Liyang <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

---
arch/x86/kernel/apic/vector.c | 17 ++++-------------
1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index bb6f7a2148d7..a75de0792942 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -218,7 +218,8 @@ static int reserve_irq_vector(struct irq_data *irqd)
return 0;
}

-static int allocate_vector(struct irq_data *irqd, const struct cpumask *dest)
+static int
+assign_vector_locked(struct irq_data *irqd, const struct cpumask *dest)
{
struct apic_chip_data *apicd = apic_chip_data(irqd);
bool resvd = apicd->has_reserved;
@@ -236,22 +237,12 @@ static int allocate_vector(struct irq_data *irqd, const struct cpumask *dest)
return 0;

vector = irq_matrix_alloc(vector_matrix, dest, resvd, &cpu);
- if (vector > 0)
- apic_update_vector(irqd, vector, cpu);
trace_vector_alloc(irqd->irq, vector, resvd, vector);
- return vector;
-}
-
-static int assign_vector_locked(struct irq_data *irqd,
- const struct cpumask *dest)
-{
- struct apic_chip_data *apicd = apic_chip_data(irqd);
- int vector = allocate_vector(irqd, dest);
-
if (vector < 0)
return vector;
+ apic_update_vector(irqd, vector, cpu);
+ apic_update_irq_cfg(irqd, vector, cpu);

- apic_update_irq_cfg(irqd, apicd->vector, apicd->cpu);
return 0;
}