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Subject[PATCH v2 3/8] dma-debug: Refactor dma_debug_entry allocation
Date
Make the prealloc_memory() logic a little more general and robust so
that it serves for runtime reallocations too. The first thing we can
do with that is clean up dma_debug_resize_entries() a bit.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---

v2: Give it a better name, simplify the locking mess

kernel/dma/debug.c | 87 +++++++++++++++++++---------------------------
1 file changed, 36 insertions(+), 51 deletions(-)

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 29486eb9d1dc..1b0858d7edfd 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -646,6 +646,36 @@ static void add_dma_entry(struct dma_debug_entry *entry)
*/
}

+static int dma_debug_add_entries(u32 num_entries, gfp_t gfp)
+{
+ struct dma_debug_entry *entry, *next_entry;
+ LIST_HEAD(tmp);
+ int i;
+
+ for (i = 0; i < num_entries; ++i) {
+ entry = kzalloc(sizeof(*entry), gfp);
+ if (!entry)
+ goto out_err;
+
+ list_add_tail(&entry->list, &tmp);
+ }
+
+ list_splice(&tmp, &free_entries);
+ num_free_entries += num_entries;
+ nr_total_entries += num_entries;
+
+ return 0;
+
+out_err:
+
+ list_for_each_entry_safe(entry, next_entry, &tmp, list) {
+ list_del(&entry->list);
+ kfree(entry);
+ }
+
+ return -ENOMEM;
+}
+
static struct dma_debug_entry *__dma_entry_alloc(void)
{
struct dma_debug_entry *entry;
@@ -715,28 +745,13 @@ int dma_debug_resize_entries(u32 num_entries)
int i, delta, ret = 0;
unsigned long flags;
struct dma_debug_entry *entry;
- LIST_HEAD(tmp);

spin_lock_irqsave(&free_entries_lock, flags);

if (nr_total_entries < num_entries) {
delta = num_entries - nr_total_entries;

- spin_unlock_irqrestore(&free_entries_lock, flags);
-
- for (i = 0; i < delta; i++) {
- entry = kzalloc(sizeof(*entry), GFP_KERNEL);
- if (!entry)
- break;
-
- list_add_tail(&entry->list, &tmp);
- }
-
- spin_lock_irqsave(&free_entries_lock, flags);
-
- list_splice(&tmp, &free_entries);
- nr_total_entries += i;
- num_free_entries += i;
+ ret = dma_debug_add_entries(delta, GFP_ATOMIC);
} else {
delta = nr_total_entries - num_entries;

@@ -746,11 +761,10 @@ int dma_debug_resize_entries(u32 num_entries)
}

nr_total_entries -= i;
+ if (nr_total_entries != num_entries)
+ ret = -EBUSY;
}

- if (nr_total_entries != num_entries)
- ret = 1;
-
spin_unlock_irqrestore(&free_entries_lock, flags);

return ret;
@@ -764,36 +778,6 @@ int dma_debug_resize_entries(u32 num_entries)
* 2. Preallocate a given number of dma_debug_entry structs
*/

-static int prealloc_memory(u32 num_entries)
-{
- struct dma_debug_entry *entry, *next_entry;
- int i;
-
- for (i = 0; i < num_entries; ++i) {
- entry = kzalloc(sizeof(*entry), GFP_KERNEL);
- if (!entry)
- goto out_err;
-
- list_add_tail(&entry->list, &free_entries);
- }
-
- num_free_entries = num_entries;
- min_free_entries = num_entries;
-
- pr_info("preallocated %d debug entries\n", num_entries);
-
- return 0;
-
-out_err:
-
- list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
- list_del(&entry->list);
- kfree(entry);
- }
-
- return -ENOMEM;
-}
-
static ssize_t filter_read(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
@@ -1038,14 +1022,15 @@ static int dma_debug_init(void)
return 0;
}

- if (prealloc_memory(nr_prealloc_entries) != 0) {
+ if (dma_debug_add_entries(nr_prealloc_entries, GFP_KERNEL) != 0) {
pr_err("debugging out of memory error - disabled\n");
global_disable = true;

return 0;
}

- nr_total_entries = num_free_entries;
+ min_free_entries = num_free_entries;
+ pr_info("preallocated %d debug entries\n", nr_total_entries);

dma_debug_initialized = true;

--
2.19.1.dirty
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