ACPI, APEI, Add ERST record ID cache
APEI ERST firmware interface and implementation has no multiple users
in mind. For example, if there is four records in storage with ID: 1,
2, 3 and 4, if two ERST readers enumerate the records via
GET_NEXT_RECORD_ID as follow,
reader 1 reader 2
1
2
3
4
-1
-1
where -1 signals there is no more record ID.
Reader 1 has no chance to check record 2 and 4, while reader 2 has no
chance to check record 1 and 3. And any other GET_NEXT_RECORD_ID will
return -1, that is, other readers will has no chance to check any
record even they are not cleared by anyone.
This makes raw GET_NEXT_RECORD_ID not suitable for used by multiple
users.
To solve the issue, an in-memory ERST record ID cache is designed and
implemented. When enumerating record ID, the ID returned by
GET_NEXT_RECORD_ID is added into cache in addition to be returned to
caller. So other readers can check the cache to get all record ID
available.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/apei/erst-dbg.c b/drivers/acpi/apei/erst-dbg.c
index de73caf..a4cfb64 100644
--- a/drivers/acpi/apei/erst-dbg.c
+++ b/drivers/acpi/apei/erst-dbg.c
@@ -43,12 +43,27 @@
static int erst_dbg_open(struct inode *inode, struct file *file)
{
+ int rc, *pos;
+
if (erst_disable)
return -ENODEV;
+ pos = (int *)&file->private_data;
+
+ rc = erst_get_record_id_begin(pos);
+ if (rc)
+ return rc;
+
return nonseekable_open(inode, file);
}
+static int erst_dbg_release(struct inode *inode, struct file *file)
+{
+ erst_get_record_id_end();
+
+ return 0;
+}
+
static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
int rc;
@@ -79,18 +94,20 @@
static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
size_t usize, loff_t *off)
{
- int rc;
+ int rc, *pos;
ssize_t len = 0;
u64 id;
- if (*off != 0)
+ if (*off)
return -EINVAL;
if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
return -EINTR;
+ pos = (int *)&filp->private_data;
+
retry_next:
- rc = erst_get_next_record_id(&id);
+ rc = erst_get_record_id_next(pos, &id);
if (rc)
goto out;
/* no more record */
@@ -181,6 +198,7 @@
static const struct file_operations erst_dbg_ops = {
.owner = THIS_MODULE,
.open = erst_dbg_open,
+ .release = erst_dbg_release,
.read = erst_dbg_read,
.write = erst_dbg_write,
.unlocked_ioctl = erst_dbg_ioctl,