| Message ID | 20140627192904.GA21254@redhat.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
On Fri, 27 Jun 2014, Mike Snitzer wrote: > On Fri, Jun 27 2014 at 2:44pm -0400, > Mikulas Patocka <mpatocka@redhat.com> wrote: > > > > > > > On Fri, 27 Jun 2014, Joe Thornber wrote: > > > > > On Fri, Jun 27, 2014 at 12:01:30PM +0800, Minfei Huang wrote: > > > > The io address in callback function will become the danging point, > > > > cause by the thread of sync io wakes up by other threads > > > > and return to relieve the io address, > > > > > > Yes, well found. I prefer the following fix however. > > > > > > - Joe > > > > It seems ok. > > > > The patch is too big, I think the only change that needs to be done to fix > > the bug is to replace "struct task_struct *sleeper;" with "struct > > completion *completion;", replace "if (io->sleeper) > > wake_up_process(io->sleeper);" with "if (io->completion) > > complete(io->completion);" and declare the completion in sync_io() and > > wait on it instead of "while (1)" loop there. > > Here is the minimalist fix you suggested (I agree that splitting out a > minimalist fix is useful): Acked-by: Mikulas Patocka <mpatocka@redhat.com> > drivers/md/dm-io.c | 22 ++++++++-------------- > 1 file changed, 8 insertions(+), 14 deletions(-) > > diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c > index 2a20986..e60c2ea 100644 > --- a/drivers/md/dm-io.c > +++ b/drivers/md/dm-io.c > @@ -10,6 +10,7 @@ > #include <linux/device-mapper.h> > > #include <linux/bio.h> > +#include <linux/completion.h> > #include <linux/mempool.h> > #include <linux/module.h> > #include <linux/sched.h> > @@ -32,7 +33,7 @@ struct dm_io_client { > struct io { > unsigned long error_bits; > atomic_t count; > - struct task_struct *sleeper; > + struct completion *wait; > struct dm_io_client *client; > io_notify_fn callback; > void *context; > @@ -121,8 +122,8 @@ static void dec_count(struct io *io, unsigned int region, int error) > invalidate_kernel_vmap_range(io->vma_invalidate_address, > io->vma_invalidate_size); > > - if (io->sleeper) > - wake_up_process(io->sleeper); > + if (io->wait) > + complete(io->wait); > > else { > unsigned long r = io->error_bits; > @@ -385,6 +386,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions, > */ > volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1]; > struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io)); > + DECLARE_COMPLETION_ONSTACK(wait); > > if (num_regions > 1 && (rw & RW_MASK) != WRITE) { > WARN_ON(1); > @@ -393,7 +395,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions, > > io->error_bits = 0; > atomic_set(&io->count, 1); /* see dispatch_io() */ > - io->sleeper = current; > + io->wait = &wait; > io->client = client; > > io->vma_invalidate_address = dp->vma_invalidate_address; > @@ -401,15 +403,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions, > > dispatch_io(rw, num_regions, where, dp, io, 1); > > - while (1) { > - set_current_state(TASK_UNINTERRUPTIBLE); > - > - if (!atomic_read(&io->count)) > - break; > - > - io_schedule(); > - } > - set_current_state(TASK_RUNNING); > + wait_for_completion_io(&wait); > > if (error_bits) > *error_bits = io->error_bits; > @@ -432,7 +426,7 @@ static int async_io(struct dm_io_client *client, unsigned int num_regions, > io = mempool_alloc(client->pool, GFP_NOIO); > io->error_bits = 0; > atomic_set(&io->count, 1); /* see dispatch_io() */ > - io->sleeper = NULL; > + io->wait = NULL; > io->client = client; > io->callback = fn; > io->context = context; > -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c index 2a20986..e60c2ea 100644 --- a/drivers/md/dm-io.c +++ b/drivers/md/dm-io.c @@ -10,6 +10,7 @@ #include <linux/device-mapper.h> #include <linux/bio.h> +#include <linux/completion.h> #include <linux/mempool.h> #include <linux/module.h> #include <linux/sched.h> @@ -32,7 +33,7 @@ struct dm_io_client { struct io { unsigned long error_bits; atomic_t count; - struct task_struct *sleeper; + struct completion *wait; struct dm_io_client *client; io_notify_fn callback; void *context; @@ -121,8 +122,8 @@ static void dec_count(struct io *io, unsigned int region, int error) invalidate_kernel_vmap_range(io->vma_invalidate_address, io->vma_invalidate_size); - if (io->sleeper) - wake_up_process(io->sleeper); + if (io->wait) + complete(io->wait); else { unsigned long r = io->error_bits; @@ -385,6 +386,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions, */ volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1]; struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io)); + DECLARE_COMPLETION_ONSTACK(wait); if (num_regions > 1 && (rw & RW_MASK) != WRITE) { WARN_ON(1); @@ -393,7 +395,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions, io->error_bits = 0; atomic_set(&io->count, 1); /* see dispatch_io() */ - io->sleeper = current; + io->wait = &wait; io->client = client; io->vma_invalidate_address = dp->vma_invalidate_address; @@ -401,15 +403,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions, dispatch_io(rw, num_regions, where, dp, io, 1); - while (1) { - set_current_state(TASK_UNINTERRUPTIBLE); - - if (!atomic_read(&io->count)) - break; - - io_schedule(); - } - set_current_state(TASK_RUNNING); + wait_for_completion_io(&wait); if (error_bits) *error_bits = io->error_bits; @@ -432,7 +426,7 @@ static int async_io(struct dm_io_client *client, unsigned int num_regions, io = mempool_alloc(client->pool, GFP_NOIO); io->error_bits = 0; atomic_set(&io->count, 1); /* see dispatch_io() */ - io->sleeper = NULL; + io->wait = NULL; io->client = client; io->callback = fn; io->context = context;