x86: change flush_tlb_others to take a const struct cpumask

Impact: reduce stack usage, use new cpumask API.

This is made a little more tricky by uv_flush_tlb_others which
actually alters its argument, for an IPI to be sent to the remaining
cpus in the mask.

I solve this by allocating a cpumask_var_t for this case and falling back
to IPI should this fail.

To eliminate temporaries in the caller, all flush_tlb_others implementations
now do the this-cpu-elimination step themselves.

Note also the curious "cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask)"
which has been there since pre-git and yet f->flush_cpumask is always zero
at this point.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>

1 files changed, 33 insertions, 28 deletions

diff --git a/arch/x86/kernel/tlb_64.c b/arch/x86/kernel/tlb_64.c
index f8be6f1..38836ae 100644
--- a/arch/x86/kernel/tlb_64.c
+++ b/arch/x86/kernel/tlb_64.c
@@ -43,10 +43,10 @@
 
 union smp_flush_state {
 	struct {
-		cpumask_t flush_cpumask;
 		struct mm_struct *flush_mm;
 		unsigned long flush_va;
 		spinlock_t tlbstate_lock;
+		DECLARE_BITMAP(flush_cpumask, NR_CPUS);
 	};
 	char pad[SMP_CACHE_BYTES];
 } ____cacheline_aligned;
@@ -131,7 +131,7 @@ asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs)
 	sender = ~regs->orig_ax - INVALIDATE_TLB_VECTOR_START;
 	f = &per_cpu(flush_state, sender);
 
-	if (!cpu_isset(cpu, f->flush_cpumask))
+	if (!cpumask_test_cpu(cpu, to_cpumask(f->flush_cpumask)))
 		goto out;
 		/*
 		 * This was a BUG() but until someone can quote me the
@@ -153,19 +153,15 @@ asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs)
 	}
 out:
 	ack_APIC_irq();
-	cpu_clear(cpu, f->flush_cpumask);
+	cpumask_clear_cpu(cpu, to_cpumask(f->flush_cpumask));
 	inc_irq_stat(irq_tlb_count);
 }
 
-void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
-			     unsigned long va)
+static void flush_tlb_others_ipi(const struct cpumask *cpumask,
+				 struct mm_struct *mm, unsigned long va)
 {
 	int sender;
 	union smp_flush_state *f;
-	cpumask_t cpumask = *cpumaskp;
-
-	if (is_uv_system() && uv_flush_tlb_others(&cpumask, mm, va))
-		return;
 
 	/* Caller has disabled preemption */
 	sender = smp_processor_id() % NUM_INVALIDATE_TLB_VECTORS;
@@ -180,7 +176,8 @@ void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
 
 	f->flush_mm = mm;
 	f->flush_va = va;
-	cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask);
+	cpumask_andnot(to_cpumask(f->flush_cpumask),
+		       cpumask, cpumask_of(smp_processor_id()));
 
 	/*
 	 * Make the above memory operations globally visible before
@@ -191,9 +188,9 @@ void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
 	 * We have to send the IPI only to
 	 * CPUs affected.
 	 */
-	send_IPI_mask(&cpumask, INVALIDATE_TLB_VECTOR_START + sender);
+	send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR_START + sender);
 
-	while (!cpus_empty(f->flush_cpumask))
+	while (!cpumask_empty(to_cpumask(f->flush_cpumask)))
 		cpu_relax();
 
 	f->flush_mm = NULL;
@@ -201,6 +198,24 @@ void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
 	spin_unlock(&f->tlbstate_lock);
 }
 
+void native_flush_tlb_others(const struct cpumask *cpumask,
+			     struct mm_struct *mm, unsigned long va)
+{
+	if (is_uv_system()) {
+		cpumask_var_t after_uv_flush;
+
+		if (alloc_cpumask_var(&after_uv_flush, GFP_ATOMIC)) {
+			cpumask_andnot(after_uv_flush,
+				       cpumask, cpumask_of(smp_processor_id()));
+			if (!uv_flush_tlb_others(after_uv_flush, mm, va))
+				flush_tlb_others_ipi(after_uv_flush, mm, va);
+			free_cpumask_var(after_uv_flush);
+			return;
+		}
+	}
+	flush_tlb_others_ipi(cpumask, mm, va);
+}
+
 static int __cpuinit init_smp_flush(void)
 {
 	int i;
@@ -215,25 +230,18 @@ core_initcall(init_smp_flush);
 void flush_tlb_current_task(void)
 {
 	struct mm_struct *mm = current->mm;
-	cpumask_t cpu_mask;
 
 	preempt_disable();
-	cpu_mask = mm->cpu_vm_mask;
-	cpu_clear(smp_processor_id(), cpu_mask);
 
 	local_flush_tlb();
-	if (!cpus_empty(cpu_mask))
-		flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);
+	if (cpumask_any_but(&mm->cpu_vm_mask, smp_processor_id()) < nr_cpu_ids)
+		flush_tlb_others(&mm->cpu_vm_mask, mm, TLB_FLUSH_ALL);
 	preempt_enable();
 }
 
 void flush_tlb_mm(struct mm_struct *mm)
 {
-	cpumask_t cpu_mask;
-
 	preempt_disable();
-	cpu_mask = mm->cpu_vm_mask;
-	cpu_clear(smp_processor_id(), cpu_mask);
 
 	if (current->active_mm == mm) {
 		if (current->mm)
@@ -241,8 +249,8 @@ void flush_tlb_mm(struct mm_struct *mm)
 		else
 			leave_mm(smp_processor_id());
 	}
-	if (!cpus_empty(cpu_mask))
-		flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);
+	if (cpumask_any_but(&mm->cpu_vm_mask, smp_processor_id()) < nr_cpu_ids)
+		flush_tlb_others(&mm->cpu_vm_mask, mm, TLB_FLUSH_ALL);
 
 	preempt_enable();
 }
@@ -250,11 +258,8 @@ void flush_tlb_mm(struct mm_struct *mm)
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	cpumask_t cpu_mask;
 
 	preempt_disable();
-	cpu_mask = mm->cpu_vm_mask;
-	cpu_clear(smp_processor_id(), cpu_mask);
 
 	if (current->active_mm == mm) {
 		if (current->mm)
@@ -263,8 +268,8 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
 			leave_mm(smp_processor_id());
 	}
 
-	if (!cpus_empty(cpu_mask))
-		flush_tlb_others(cpu_mask, mm, va);
+	if (cpumask_any_but(&mm->cpu_vm_mask, smp_processor_id()) < nr_cpu_ids)
+		flush_tlb_others(&mm->cpu_vm_mask, mm, va);
 
 	preempt_enable();
 }