[PATCH 13/26] ppc: Convert mmu context allocation to new IDA API

From: Matthew Wilcox
Date: Thu Jun 21 2018 - 17:33:52 EST


ida_alloc_range is the perfect fit for this use case. Eliminates
a custom spinlock, a call to ida_pre_get and a local check for the
allocated ID exceeding a maximum.

Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
---
arch/powerpc/mm/mmu_context_book3s64.c | 44 +++-----------------------
1 file changed, 4 insertions(+), 40 deletions(-)

diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c
index f3d4b4a0e561..5a0cf2cc8ba0 100644
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -26,48 +26,16 @@
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>

-static DEFINE_SPINLOCK(mmu_context_lock);
static DEFINE_IDA(mmu_context_ida);

static int alloc_context_id(int min_id, int max_id)
{
- int index, err;
-
-again:
- if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
- return -ENOMEM;
-
- spin_lock(&mmu_context_lock);
- err = ida_get_new_above(&mmu_context_ida, min_id, &index);
- spin_unlock(&mmu_context_lock);
-
- if (err == -EAGAIN)
- goto again;
- else if (err)
- return err;
-
- if (index > max_id) {
- spin_lock(&mmu_context_lock);
- ida_remove(&mmu_context_ida, index);
- spin_unlock(&mmu_context_lock);
- return -ENOMEM;
- }
-
- return index;
+ return ida_alloc_range(&mmu_context_ida, min_id, max_id, GFP_KERNEL);
}

void hash__reserve_context_id(int id)
{
- int rc, result = 0;
-
- do {
- if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
- break;
-
- spin_lock(&mmu_context_lock);
- rc = ida_get_new_above(&mmu_context_ida, id, &result);
- spin_unlock(&mmu_context_lock);
- } while (rc == -EAGAIN);
+ int result = ida_alloc_range(&mmu_context_ida, id, id, GFP_KERNEL);

WARN(result != id, "mmu: Failed to reserve context id %d (rc %d)\n", id, result);
}
@@ -172,9 +140,7 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)

void __destroy_context(int context_id)
{
- spin_lock(&mmu_context_lock);
- ida_remove(&mmu_context_ida, context_id);
- spin_unlock(&mmu_context_lock);
+ ida_free(&mmu_context_ida, context_id);
}
EXPORT_SYMBOL_GPL(__destroy_context);

@@ -182,13 +148,11 @@ static void destroy_contexts(mm_context_t *ctx)
{
int index, context_id;

- spin_lock(&mmu_context_lock);
for (index = 0; index < ARRAY_SIZE(ctx->extended_id); index++) {
context_id = ctx->extended_id[index];
if (context_id)
- ida_remove(&mmu_context_ida, context_id);
+ ida_free(&mmu_context_ida, context_id);
}
- spin_unlock(&mmu_context_lock);
}

static void pte_frag_destroy(void *pte_frag)
--
2.17.1