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Subject[patch] x86, irq: allow 0xff for /proc/irq/[n]/smp_affinity on a 8 cpu system
From
Date
John Blackwood reported:
> on an older Dell PowerEdge 6650 system with 8 cpus (4 are hyper-threaded),
> and 32 bit (x86) kernel, once you change the irq smp_affinity of an irq
> to be less than all cpus in the system, you can never change really the
> irq smp_affinity back to be all cpus in the system (0xff) again,
> even though no error status is returned on the "/bin/echo ff >
> /proc/irq/[n]/smp_affinity" operation.
>
> This is due to that fact that BAD_APICID has the same value as
> all cpus (0xff) on 32bit kernels, and thus the value returned from
> set_desc_affinity() via the cpu_mask_to_apicid_and() function is treated
> as a failure in set_ioapic_affinity_irq_desc(), and no affinity changes
> are made.

set_desc_affinity() is already checking if the incoming cpu mask
intersects with the cpu online mask or not. So there is no need
for the apic op cpu_mask_to_apicid_and() to check again
and return BAD_APICID.

Remove the BAD_APICID return value from cpu_mask_to_apicid_and()
and also fix set_desc_affinity() to return -1 instead of using BAD_APICID
to represent error conditions (as cpu_mask_to_apicid_and() can return
logical or physical apicid values and BAD_APICID is really to represent
bad physical apic id).

Reported-by: John Blackwood <john.blackwood@ccur.com>
Root-caused-by: John Blackwood <john.blackwood@ccur.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
---
arch/x86/include/asm/hw_irq.h | 3 ++-
arch/x86/kernel/apic/apic_flat_64.c | 5 +----
arch/x86/kernel/apic/bigsmp_32.c | 5 +----
arch/x86/kernel/apic/io_apic.c | 32 ++++++++++++++------------------
arch/x86/kernel/apic/x2apic_cluster.c | 5 +----
arch/x86/kernel/apic/x2apic_phys.c | 5 +----
arch/x86/kernel/apic/x2apic_uv_x.c | 5 +----
arch/x86/kernel/uv_irq.c | 3 +--
8 files changed, 22 insertions(+), 41 deletions(-)
diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index 08c48a8..eeac829 100644
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -103,7 +103,8 @@ extern int assign_irq_vector(int, struct irq_cfg *, const struct cpumask *);
extern void send_cleanup_vector(struct irq_cfg *);

struct irq_desc;
-extern unsigned int set_desc_affinity(struct irq_desc *, const struct cpumask *);
+extern unsigned int set_desc_affinity(struct irq_desc *, const struct cpumask *,
+ unsigned int *dest_id);
extern int IO_APIC_get_PCI_irq_vector(int bus, int devfn, int pin, struct io_apic_irq_attr *irq_attr);
extern void setup_ioapic_dest(void);

diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c
index d0c99ab..eacbd2b 100644
--- a/arch/x86/kernel/apic/apic_flat_64.c
+++ b/arch/x86/kernel/apic/apic_flat_64.c
@@ -306,10 +306,7 @@ physflat_cpu_mask_to_apicid_and(const struct cpumask *cpumask,
if (cpumask_test_cpu(cpu, cpu_online_mask))
break;
}
- if (cpu < nr_cpu_ids)
- return per_cpu(x86_cpu_to_apicid, cpu);
-
- return BAD_APICID;
+ return per_cpu(x86_cpu_to_apicid, cpu);
}

struct apic apic_physflat = {
diff --git a/arch/x86/kernel/apic/bigsmp_32.c b/arch/x86/kernel/apic/bigsmp_32.c
index 38dcecf..cb804c5 100644
--- a/arch/x86/kernel/apic/bigsmp_32.c
+++ b/arch/x86/kernel/apic/bigsmp_32.c
@@ -131,10 +131,7 @@ static unsigned int bigsmp_cpu_mask_to_apicid_and(const struct cpumask *cpumask,
if (cpumask_test_cpu(cpu, cpu_online_mask))
break;
}
- if (cpu < nr_cpu_ids)
- return bigsmp_cpu_to_logical_apicid(cpu);
-
- return BAD_APICID;
+ return bigsmp_cpu_to_logical_apicid(cpu);
}

static int bigsmp_phys_pkg_id(int cpuid_apic, int index_msb)
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 11a5851..de00c46 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2276,26 +2276,28 @@ static void __target_IO_APIC_irq(unsigned int irq, unsigned int dest, struct irq

/*
* Either sets desc->affinity to a valid value, and returns
- * ->cpu_mask_to_apicid of that, or returns BAD_APICID and
+ * ->cpu_mask_to_apicid of that in dest_id, or returns -1 and
* leaves desc->affinity untouched.
*/
unsigned int
-set_desc_affinity(struct irq_desc *desc, const struct cpumask *mask)
+set_desc_affinity(struct irq_desc *desc, const struct cpumask *mask,
+ unsigned int *dest_id)
{
struct irq_cfg *cfg;
unsigned int irq;

if (!cpumask_intersects(mask, cpu_online_mask))
- return BAD_APICID;
+ return -1;

irq = desc->irq;
cfg = desc->chip_data;
if (assign_irq_vector(irq, cfg, mask))
- return BAD_APICID;
+ return -1;

cpumask_copy(desc->affinity, mask);

- return apic->cpu_mask_to_apicid_and(desc->affinity, cfg->domain);
+ *dest_id = apic->cpu_mask_to_apicid_and(desc->affinity, cfg->domain);
+ return 0;
}

static int
@@ -2311,12 +2313,11 @@ set_ioapic_affinity_irq_desc(struct irq_desc *desc, const struct cpumask *mask)
cfg = desc->chip_data;

spin_lock_irqsave(&ioapic_lock, flags);
- dest = set_desc_affinity(desc, mask);
- if (dest != BAD_APICID) {
+ ret = set_desc_affinity(desc, mask, &dest);
+ if (!ret) {
/* Only the high 8 bits are valid. */
dest = SET_APIC_LOGICAL_ID(dest);
__target_IO_APIC_irq(irq, dest, cfg);
- ret = 0;
}
spin_unlock_irqrestore(&ioapic_lock, flags);

@@ -3351,8 +3352,7 @@ static int set_msi_irq_affinity(unsigned int irq, const struct cpumask *mask)
struct msi_msg msg;
unsigned int dest;

- dest = set_desc_affinity(desc, mask);
- if (dest == BAD_APICID)
+ if (set_desc_affinity(desc, mask, &dest))
return -1;

cfg = desc->chip_data;
@@ -3384,8 +3384,7 @@ ir_set_msi_irq_affinity(unsigned int irq, const struct cpumask *mask)
if (get_irte(irq, &irte))
return -1;

- dest = set_desc_affinity(desc, mask);
- if (dest == BAD_APICID)
+ if (set_desc_affinity(desc, mask, &dest))
return -1;

irte.vector = cfg->vector;
@@ -3567,8 +3566,7 @@ static int dmar_msi_set_affinity(unsigned int irq, const struct cpumask *mask)
struct msi_msg msg;
unsigned int dest;

- dest = set_desc_affinity(desc, mask);
- if (dest == BAD_APICID)
+ if (set_desc_affinity(desc, mask, &dest))
return -1;

cfg = desc->chip_data;
@@ -3623,8 +3621,7 @@ static int hpet_msi_set_affinity(unsigned int irq, const struct cpumask *mask)
struct msi_msg msg;
unsigned int dest;

- dest = set_desc_affinity(desc, mask);
- if (dest == BAD_APICID)
+ if (set_desc_affinity(desc, mask, &dest))
return -1;

cfg = desc->chip_data;
@@ -3730,8 +3727,7 @@ static int set_ht_irq_affinity(unsigned int irq, const struct cpumask *mask)
struct irq_cfg *cfg;
unsigned int dest;

- dest = set_desc_affinity(desc, mask);
- if (dest == BAD_APICID)
+ if (set_desc_affinity(desc, mask, &dest))
return -1;

cfg = desc->chip_data;
diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index a5371ec..cf69c59 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -148,10 +148,7 @@ x2apic_cpu_mask_to_apicid_and(const struct cpumask *cpumask,
break;
}

- if (cpu < nr_cpu_ids)
- return per_cpu(x86_cpu_to_logical_apicid, cpu);
-
- return BAD_APICID;
+ return per_cpu(x86_cpu_to_logical_apicid, cpu);
}

static unsigned int x2apic_cluster_phys_get_apic_id(unsigned long x)
diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
index a8989aa..8972f38 100644
--- a/arch/x86/kernel/apic/x2apic_phys.c
+++ b/arch/x86/kernel/apic/x2apic_phys.c
@@ -146,10 +146,7 @@ x2apic_cpu_mask_to_apicid_and(const struct cpumask *cpumask,
break;
}

- if (cpu < nr_cpu_ids)
- return per_cpu(x86_cpu_to_apicid, cpu);
-
- return BAD_APICID;
+ return per_cpu(x86_cpu_to_apicid, cpu);
}

static unsigned int x2apic_phys_get_apic_id(unsigned long x)
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index b684bb3..d56b0ef 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -225,10 +225,7 @@ uv_cpu_mask_to_apicid_and(const struct cpumask *cpumask,
if (cpumask_test_cpu(cpu, cpu_online_mask))
break;
}
- if (cpu < nr_cpu_ids)
- return per_cpu(x86_cpu_to_apicid, cpu);
-
- return BAD_APICID;
+ return per_cpu(x86_cpu_to_apicid, cpu);
}

static unsigned int x2apic_get_apic_id(unsigned long x)
diff --git a/arch/x86/kernel/uv_irq.c b/arch/x86/kernel/uv_irq.c
index 61d805d..ece73d8 100644
--- a/arch/x86/kernel/uv_irq.c
+++ b/arch/x86/kernel/uv_irq.c
@@ -215,8 +215,7 @@ static int uv_set_irq_affinity(unsigned int irq, const struct cpumask *mask)
unsigned long mmr_offset;
unsigned mmr_pnode;

- dest = set_desc_affinity(desc, mask);
- if (dest == BAD_APICID)
+ if (set_desc_affinity(desc, mask, &dest))
return -1;

mmr_value = 0;



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