The patch titled /proc/swaps: support polling has been added to the -mm tree. Its filename is proc-swaps-support-polling.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: /proc/swaps: support polling From: Kay Sievers <kay.sievers@xxxxxxxx> System management wants to subscribe to changes in swap configuration. Make /proc/swaps pollable like /proc/mounts. Signed-off-by: Kay Sievers <kay.sievers@xxxxxxxx> Cc: Greg KH <greg@xxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/swapfile.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) diff -puN mm/swapfile.c~proc-swaps-support-polling mm/swapfile.c --- a/mm/swapfile.c~proc-swaps-support-polling +++ a/mm/swapfile.c @@ -30,6 +30,7 @@ #include <linux/capability.h> #include <linux/syscalls.h> #include <linux/memcontrol.h> +#include <linux/poll.h> #include <asm/pgtable.h> #include <asm/tlbflush.h> @@ -58,6 +59,9 @@ static struct swap_info_struct *swap_inf static DEFINE_MUTEX(swapon_mutex); +static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); +static atomic_t proc_poll_event = ATOMIC_INIT(0); + static inline unsigned char swap_count(unsigned char ent) { return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ @@ -1680,6 +1684,8 @@ SYSCALL_DEFINE1(swapoff, const char __us } filp_close(swap_file, NULL); err = 0; + atomic_inc(&proc_poll_event); + wake_up_interruptible(&proc_poll_wait); out_dput: filp_close(victim, NULL); @@ -1688,6 +1694,25 @@ out: } #ifdef CONFIG_PROC_FS +struct proc_swaps { + struct seq_file seq; + int event; +}; + +static unsigned swaps_poll(struct file *file, poll_table *wait) +{ + struct proc_swaps *s = file->private_data; + + poll_wait(file, &proc_poll_wait, wait); + + if (s->event != atomic_read(&proc_poll_event)) { + s->event = atomic_read(&proc_poll_event); + return POLLIN | POLLRDNORM | POLLERR | POLLPRI; + } + + return POLLIN | POLLRDNORM; +} + /* iterator */ static void *swap_start(struct seq_file *swap, loff_t *pos) { @@ -1771,7 +1796,24 @@ static const struct seq_operations swaps static int swaps_open(struct inode *inode, struct file *file) { - return seq_open(file, &swaps_op); + struct proc_swaps *s; + int ret; + + s = kmalloc(sizeof(struct proc_swaps), GFP_KERNEL); + if (!s) + return -ENOMEM; + + file->private_data = s; + + ret = seq_open(file, &swaps_op); + if (ret) { + kfree(s); + return ret; + } + + s->seq.private = s; + s->event = atomic_read(&proc_poll_event); + return ret; } static const struct file_operations proc_swaps_operations = { @@ -1779,6 +1821,7 @@ static const struct file_operations proc .read = seq_read, .llseek = seq_lseek, .release = seq_release, + .poll = swaps_poll, }; static int __init procswaps_init(void) @@ -2084,6 +2127,9 @@ SYSCALL_DEFINE2(swapon, const char __use swap_info[prev]->next = type; spin_unlock(&swap_lock); mutex_unlock(&swapon_mutex); + atomic_inc(&proc_poll_event); + wake_up_interruptible(&proc_poll_wait); + error = 0; goto out; bad_swap: _ Patches currently in -mm which might be from kay.sievers@xxxxxxxx are linux-next.patch proc-swaps-support-polling.patch proc-swaps-support-polling-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html