implement FASYNC capability to /dev/mem_notify.
<usage example>
fd = open("/dev/mem_notify", O_RDONLY);
fcntl(fd, F_SETOWN, getpid());
flags = fcntl(fd, F_GETFL);
fcntl(fd, F_SETFL, flags|FASYNC); /* when low memory, receive SIGIO */
</usage example>
ChangeLog
v5: new
Signed-off-by: KOSAKI Motohiro <[EMAIL PROTECTED]>
---
mm/mem_notify.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 90 insertions(+), 5 deletions(-)
Index: b/mm/mem_notify.c
===================================================================
--- a/mm/mem_notify.c 2008-01-23 23:09:08.000000000 +0900
+++ b/mm/mem_notify.c 2008-01-23 23:09:27.000000000 +0900
@@ -23,18 +23,58 @@
#define PROC_WAKEUP_GUARD (10*HZ)
struct mem_notify_file_info {
- unsigned long last_proc_notify;
+ unsigned long last_proc_notify;
+ struct file *file;
+
+ struct list_head fa_list;
+ int fa_fd;
};
static DECLARE_WAIT_QUEUE_HEAD(mem_wait);
static atomic_long_t nr_under_memory_pressure_zones = ATOMIC_LONG_INIT(0);
static atomic_t nr_watcher_task = ATOMIC_INIT(0);
+static LIST_HEAD(mem_notify_fasync_list);
+static DEFINE_SPINLOCK(mem_notify_fasync_lock);
+static atomic_t nr_fasync_task = ATOMIC_INIT(0);
atomic_long_t last_mem_notify = ATOMIC_LONG_INIT(INITIAL_JIFFIES);
+
+static void mem_notify_kill_fasync_nr(int sig, int band, int nr)
+{
+ struct mem_notify_file_info *iter, *saved_iter;
+ LIST_HEAD(l_fired);
+
+ if (!nr)
+ return;
+
+ spin_lock(&mem_notify_fasync_lock);
+
+ list_for_each_entry_safe_reverse(iter, saved_iter,
&mem_notify_fasync_list, fa_list) {
+ struct fown_struct * fown;
+
+ fown = &iter->file->f_owner;
+ if (!(sig == SIGURG && fown->signum == 0))
+ send_sigio(fown, iter->fa_fd, band);
+
+ list_del(&iter->fa_list);
+ list_add(&iter->fa_list, &l_fired);
+ if(!--nr)
+ break;
+ }
+
+ /* rotate moving for FIFO wakeup */
+ list_splice(&l_fired, &mem_notify_fasync_list);
+
+ spin_unlock(&mem_notify_fasync_lock);
+}
+
+
void __memory_pressure_notify(struct zone* zone, int pressure)
{
int nr_wakeup;
+ int nr_poll_wakeup = 0;
+ int nr_fasync_wakeup = 0;
int flags;
spin_lock_irqsave(&mem_wait.lock, flags);
@@ -47,13 +87,18 @@ void __memory_pressure_notify(struct zon
if (pressure) {
int nr_watcher = atomic_read(&nr_watcher_task);
+ int nr_fasync = atomic_read(&nr_fasync_task);
nr_wakeup = (nr_watcher >> 4) + 1;
if (unlikely(nr_wakeup > 100))
nr_wakeup = 100;
+ nr_fasync_wakeup = nr_wakeup * nr_fasync/nr_watcher;
+ nr_poll_wakeup = nr_wakeup - nr_fasync_wakeup;
+
atomic_long_set(&last_mem_notify, jiffies);
- wake_up_locked_nr(&mem_wait, nr_wakeup);
+ wake_up_locked_nr(&mem_wait, nr_poll_wakeup);
+ mem_notify_kill_fasync_nr(SIGIO, POLL_IN, nr_fasync_wakeup);
}
spin_unlock_irqrestore(&mem_wait.lock, flags);
@@ -71,6 +116,9 @@ static int mem_notify_open(struct inode
}
info->last_proc_notify = INITIAL_JIFFIES;
+ INIT_LIST_HEAD(&info->fa_list);
+ info->file = file;
+ info->fa_fd = -1;
file->private_data = info;
atomic_inc(&nr_watcher_task);
out:
@@ -79,7 +127,16 @@ out:
static int mem_notify_release(struct inode *inode, struct file *file)
{
- kfree(file->private_data);
+ struct mem_notify_file_info *info = file->private_data;
+
+ spin_lock(&mem_notify_fasync_lock);
+ if (!list_empty(&info->fa_list)) {
+ list_del(&info->fa_list);
+ atomic_dec(&nr_fasync_task);
+ }
+ spin_unlock(&mem_notify_fasync_lock);
+
+ kfree(info);
atomic_dec(&nr_watcher_task);
return 0;
}
@@ -106,9 +163,37 @@ out:
return retval;
}
+static int mem_notify_fasync(int fd, struct file *filp, int on)
+{
+ struct mem_notify_file_info *info = filp->private_data;
+ int result = 0;
+
+ spin_lock(&mem_notify_fasync_lock);
+ if (on) {
+ if (list_empty(&info->fa_list)) {
+ info->fa_fd = fd;
+ list_add(&info->fa_list, &mem_notify_fasync_list);
+ result = 1;
+ } else {
+ info->fa_fd = fd;
+ }
+ } else {
+ if (!list_empty(&info->fa_list)) {
+ list_del_init(&info->fa_list);
+ info->fa_fd = -1;
+ result = -1;
+ }
+ }
+ if (result != 0)
+ atomic_add(result, &nr_fasync_task);
+ spin_unlock(&mem_notify_fasync_lock);
+ return abs(result);
+}
+
struct file_operations mem_notify_fops = {
- .open = mem_notify_open,
+ .open = mem_notify_open,
.release = mem_notify_release,
- .poll = mem_notify_poll,
+ .poll = mem_notify_poll,
+ .fasync = mem_notify_fasync,
};
EXPORT_SYMBOL(mem_notify_fops);
--
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