From: Pan Xinhui <xinhuix....@intel.com>
There are many nodes in the PAT memtype rb-tree. When we dump this tree
we call kzalloc every time to copy nodes. Actually these kzalloc are not
necessary. Lets do a optimization now.
Let seq_file core create an *entry* when open and free it when release.
*entry* is stored as seq->private, so we can use it in seq_operations
callback who traverse/output the PAT memtype rb-tree only. Lots of
unnecessary kzalloc could be avoided now.
Signed-off-by: Pan Xinhui <xinhuix....@intel.com>
---
v1 -> v2:
Use seq_open/release_private. let seq_file core handle memory
alloc/free.
seq_operations callbacks now only traverse/output the PAT rb-tree.
---
arch/x86/mm/pat.c | 28 ++++++++++------------------
1 file changed, 10 insertions(+), 18 deletions(-)
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 268b2c8..53920be 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -1001,41 +1001,33 @@ EXPORT_SYMBOL_GPL(pgprot_writethrough);
#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_X86_PAT)
-static struct memtype *memtype_get_idx(loff_t pos)
+static struct memtype *memtype_get_idx(struct memtype *entry, loff_t pos)
{
- struct memtype *print_entry;
int ret;
- print_entry = kzalloc(sizeof(struct memtype), GFP_KERNEL);
- if (!print_entry)
- return NULL;
-
spin_lock(&memtype_lock);
- ret = rbt_memtype_copy_nth_element(print_entry, pos);
+ ret = rbt_memtype_copy_nth_element(entry, pos);
spin_unlock(&memtype_lock);
- if (!ret) {
- return print_entry;
- } else {
- kfree(print_entry);
- return NULL;
- }
+ return ret ? NULL : entry;
}
static void *memtype_seq_start(struct seq_file *seq, loff_t *pos)
{
+ struct memtype *entry = seq->private;
+
if (*pos == 0) {
++*pos;
seq_puts(seq, "PAT memtype list:\n");
}
- return memtype_get_idx(*pos);
+ return memtype_get_idx(entry, *pos);
}
static void *memtype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
++*pos;
- return memtype_get_idx(*pos);
+ return memtype_get_idx((struct memtype *)v, *pos);
}
static void memtype_seq_stop(struct seq_file *seq, void *v)
@@ -1048,7 +1040,6 @@ static int memtype_seq_show(struct seq_file *seq, void *v)
seq_printf(seq, "%s @ 0x%Lx-0x%Lx\n", cattr_name(print_entry->type),
print_entry->start, print_entry->end);
- kfree(print_entry);
return 0;
}
@@ -1062,14 +1053,15 @@ static const struct seq_operations memtype_seq_ops = {
static int memtype_seq_open(struct inode *inode, struct file *file)
{
- return seq_open(file, &memtype_seq_ops);
+ return seq_open_private(file, &memtype_seq_ops,
+ sizeof(struct memtype));
}
static const struct file_operations memtype_fops = {
.open = memtype_seq_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release,
+ .release = seq_release_private,
};
static int __init pat_memtype_list_init(void)
--
1.9.1
--
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