On Fri, 15 Mar 2002, Neil Brown wrote:
Compiling. Results will be available later today :)
lp
gody
PS: Can we add some printk's in the locking code (perhaps some macro,
which would do this for us), so I can see where locking is done (semaphore
setup that is). Perhaps we can easier spot lock path that way.
> On Friday March 15, neilb@cse.unsw.edu.au wrote:
> >
> > I have even tried to duplicate your results. ...
>
> Ok, here's another try. I managed to get a deadlock when creating an
> array. Your problem could well be related.
>
>
> Could you try this patch please? It changes all_mddevs_rem into a r/w
> semaphore.
>
>
> Thanks,
> NeilBrown
>
> --- ./drivers/md/md.c 2002/03/15 04:05:03 1.3
> +++ ./drivers/md/md.c 2002/03/15 04:07:37
> @@ -34,6 +34,7 @@
> #include <linux/sysctl.h>
> #include <linux/raid/xor.h>
> #include <linux/devfs_fs_kernel.h>
> +#include <linux/rwsem.h>
>
> #include <linux/init.h>
>
> @@ -149,7 +150,7 @@
> * increase ->active or take a lock
> */
> static MD_LIST_HEAD(all_mddevs);
> -static DECLARE_MUTEX(all_mddevs_sem);
> +static DECLARE_RWSEM(all_mddevs_sem);
>
> /*
> * The mapping between kdev and mddev is not necessary a simple
> @@ -164,13 +165,13 @@
> mddev_t *mddev;
> if (MAJOR(dev) != MD_MAJOR)
> BUG();
> - down(&all_mddevs_sem);
> + down_read(&all_mddevs_sem);
> mddev = mddev_map[MINOR(dev)].mddev;
> if (mddev && !mddev->dying)
> atomic_inc(&mddev->active);
> else
> mddev = NULL;
> - up(&all_mddevs_sem);
> + up_read(&all_mddevs_sem);
> return mddev;
> }
>
> @@ -179,7 +180,7 @@
> mddev_t *mddev;
> if (MAJOR(dev) != MD_MAJOR)
> BUG();
> - down(&all_mddevs_sem);
> + down_read(&all_mddevs_sem);
> mddev = mddev_map[MINOR(dev)].mddev;
> if (mddev) {
> if (mddev->dying)
> @@ -187,7 +188,7 @@
> else
> lock_mddev(mddev);
> }
> - up(&all_mddevs_sem);
> + up_read(&all_mddevs_sem);
> return mddev;
> }
> static inline mddev_t * kdev_to_mddev_lock_interruptible (kdev_t dev, int *err)
> @@ -195,7 +196,7 @@
> mddev_t *mddev;
> if (MAJOR(dev) != MD_MAJOR)
> BUG();
> - down(&all_mddevs_sem);
> + down_read(&all_mddevs_sem);
> mddev = mddev_map[MINOR(dev)].mddev;
> *err = 0;
> if (mddev) {
> @@ -205,7 +206,7 @@
> } else
> *err = lock_mddev_interruptible(mddev);
> }
> - up(&all_mddevs_sem);
> + up_read(&all_mddevs_sem);
> return mddev;
> }
>
> @@ -286,10 +287,10 @@
> * personalities can create additional mddevs
> * if necessary.
> */
> - down(&all_mddevs_sem);
> + down_write(&all_mddevs_sem);
> add_mddev_mapping(mddev, dev, 0);
> md_list_add(&mddev->all_mddevs, &all_mddevs);
> - up(&all_mddevs_sem);
> + up_write(&all_mddevs_sem);
>
> MOD_INC_USE_COUNT;
>
> @@ -798,10 +799,10 @@
> md_hd_struct[mdidx(mddev)].nr_sects = 0;
>
>
> - down(&all_mddevs_sem);
> + down_write(&all_mddevs_sem);
> del_mddev_mapping(mddev, MKDEV(MD_MAJOR, mdidx(mddev)));
> md_list_del(&mddev->all_mddevs);
> - up(&all_mddevs_sem);
> + up_write(&all_mddevs_sem);
> kfree(mddev);
> MOD_DEC_USE_COUNT;
> }
> @@ -872,7 +873,7 @@
> printk("md: **********************************\n");
> printk("md: * <COMPLETE RAID STATE PRINTOUT> *\n");
> printk("md: **********************************\n");
> -/* down(&all_mddevs_sem); */
> + down_read(&all_mddevs_sem);
> ITERATE_MDDEV/*_LOCK*/(mddev,tmp) {
> printk("md%d: ", mdidx(mddev));
>
> @@ -888,7 +889,7 @@
> ITERATE_RDEV(mddev,rdev,tmp2)
> print_rdev(rdev);
> }
> -/* up(&all_mddevs_sem); */
> + up_read(&all_mddevs_sem);
> printk("md: **********************************\n");
> printk("\n");
> }
> @@ -3252,7 +3253,7 @@
> else
> sz += sprintf(page+sz, "%d sectors\n", read_ahead[MD_MAJOR]);
>
> - down(&all_mddevs_sem);
> + down_read(&all_mddevs_sem);
> ITERATE_MDDEV_LOCK(mddev,tmp) {
> sz += sprintf(page + sz, "md%d : %sactive", mdidx(mddev),
> mddev->pers ? "" : "in");
> @@ -3297,7 +3298,7 @@
> }
> sz += sprintf(page + sz, "\n");
> }
> - up(&all_mddevs_sem);
> + up_read(&all_mddevs_sem);
> sz += status_unused(page + sz);
>
> return sz;
> @@ -3429,7 +3430,7 @@
>
> recheck:
> serialize = 0;
> - down(&all_mddevs_sem);
> + down_read(&all_mddevs_sem);
> ITERATE_MDDEV(mddev2,tmp) {
> if (mddev2 == mddev)
> continue;
> @@ -3441,7 +3442,7 @@
> break;
> }
> }
> - up(&all_mddevs_sem);
> + up_read(&all_mddevs_sem);
> if (serialize) {
> interruptible_sleep_on(&resync_wait);
> if (md_signal_pending(current)) {
> @@ -3590,7 +3591,7 @@
> printk(KERN_INFO "md: recovery thread got woken up ...\n");
>
> restart:
> - down(&all_mddevs_sem);
> + down_read(&all_mddevs_sem);
> ITERATE_MDDEV_LOCK(mddev,tmp) {
> sb = mddev->sb;
> if (!sb)
> @@ -3619,7 +3620,7 @@
> if (mddev->pers->diskop(mddev, &spare, DISKOP_SPARE_WRITE))
> continue;
> unlock_mddev(mddev);
> - up(&all_mddevs_sem);
> + up_read(&all_mddevs_sem);
> down(&mddev->recovery_sem);
> mddev->recovery_running = 1;
> err = md_do_sync(mddev, spare);
> @@ -3671,7 +3672,7 @@
> unlock_mddev(mddev);
> goto restart;
> }
> - up(&all_mddevs_sem);
> + up_read(&all_mddevs_sem);
> printk(KERN_INFO "md: recovery thread finished ...\n");
>
> }
>
>
__________________________________________________________________
| Matjaz Godec | Agenda d.o.o. | ISP for business |
| Tech. Manager | Gosposvetska 84 | WAN networks |
| gody@slon.net | si-2000 Maribor | Internet/Intranet |
| tel:+386.2.2340860 | Slovenija | Application servers |
|http://www.slon.net |http://www.agenda.si | Caldera OpenLinux |
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