On 3/17/2016 12:48 PM, Jason Gunthorpe wrote: > On Thu, Mar 17, 2016 at 10:01:55PM +0530, Devesh Sharma wrote: >> On Thu, Mar 17, 2016 at 9:42 PM, Jason Gunthorpe >> wrote: >>> On Thu, Mar 17, 2016 at 09:38:30PM +0530, Devesh Sharma wrote: >>> >>>> To my mind mutex is *not* solving the problem completely unless we >>>> make it a coarser grained lock. The possible deadlock problem still >>>> lingers around it. >>> >>> Review the last version I sent, with this statement in mind: >> >> I am sorry I lost the track of it, which one you are point..we have >> been discussion for a quite some time now! > > Not saying it is perfect, but it should be close: Jason, this is your patch since you completely tossed Devesh's work and did your own. Can you please post a corrected version of this with a proper changelog and Signed-off-by. Thanks. > --- a/drivers/infiniband/core/uverbs_main.c > +++ b/drivers/infiniband/core/uverbs_main.c > @@ -953,18 +953,20 @@ static int ib_uverbs_close(struct inode *inode, struct file *filp) > { > struct ib_uverbs_file *file = filp->private_data; > struct ib_uverbs_device *dev = file->device; > - struct ib_ucontext *ucontext = NULL; > + > + mutex_lock(&file->cleanup_mutex); > + if (file->ucontext) { > + ib_uverbs_cleanup_ucontext(file, file->ucontext); > + file->ucontext = NULL; > + } > + mutex_unlock(&file->cleanup_mutex); > > mutex_lock(&file->device->lists_mutex); > - ucontext = file->ucontext; > - file->ucontext = NULL; > if (!file->is_closed) { > list_del(&file->list); > file->is_closed = 1; > } > mutex_unlock(&file->device->lists_mutex); > - if (ucontext) > - ib_uverbs_cleanup_ucontext(file, ucontext); > > if (file->async_file) > kref_put(&file->async_file->ref, ib_uverbs_release_event_file); > @@ -1177,26 +1179,28 @@ static void ib_uverbs_free_hw_resources(struct ib_uverbs_device *uverbs_dev, > > mutex_lock(&uverbs_dev->lists_mutex); > while (!list_empty(&uverbs_dev->uverbs_file_list)) { > - struct ib_ucontext *ucontext; > - > file = list_first_entry(&uverbs_dev->uverbs_file_list, > struct ib_uverbs_file, list); > file->is_closed = 1; > - ucontext = file->ucontext; > list_del(&file->list); > - file->ucontext = NULL; > kref_get(&file->ref); > mutex_unlock(&uverbs_dev->lists_mutex); > + > /* We must release the mutex before going ahead and calling > * disassociate_ucontext. disassociate_ucontext might end up > * indirectly calling uverbs_close, for example due to freeing > * the resources (e.g mmput). > */ > ib_uverbs_event_handler(&file->event_handler, &event); > - if (ucontext) { > - ib_dev->disassociate_ucontext(ucontext); > - ib_uverbs_cleanup_ucontext(file, ucontext); > + mutex_lock(&file->cleanup_mutex); > + if (file->ucontext) { > + file->ucontext = NULL; > + mutex_unlock(&file->cleanup_mutex); > + ib_dev->disassociate_ucontext(file->ucontext); > + ib_uverbs_cleanup_ucontext(file, file->ucontext); > } > + else > + mutex_unlock(&file->cleanup_mutex); > > mutex_lock(&uverbs_dev->lists_mutex); > kref_put(&file->ref, ib_uverbs_release_file); >