Commit 4f564ff3 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Jason Gunthorpe
Browse files

drivers/mic/scif: do not use mmap_sem 



The driver uses mmap_sem for both pinned_vm accounting and
get_user_pages(). By using gup_fast() and letting the mm handle the lock
if needed, we can no longer rely on the semaphore and simplify the whole
thing.

Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent 70f8a3ca

drivers/misc/mic/scif/scif_rma.c

+11 −25
Original line number Diff line number Diff line
@@ -272,21 +272,12 @@ static inline void __scif_release_mm(struct mm_struct *mm) 


static inline int

__scif_dec_pinned_vm_lock(struct mm_struct *mm,

			  int nr_pages, bool try_lock)

			  int nr_pages)

{

	if (!mm || !nr_pages || !scif_ulimit_check)

		return 0;

	if (try_lock) {

		if (!down_write_trylock(&mm->mmap_sem)) {

			dev_err(scif_info.mdev.this_device,

				"%s %d err\n", __func__, __LINE__);

			return -1;

		}

	} else {

		down_write(&mm->mmap_sem);

	}



	atomic64_sub(nr_pages, &mm->pinned_vm);

	up_write(&mm->mmap_sem);

	return 0;

}
@@ -298,16 +289,16 @@ static inline int __scif_check_inc_pinned_vm(struct mm_struct *mm, 
	if (!mm || !nr_pages || !scif_ulimit_check)

		return 0;



	locked = nr_pages;

	locked += atomic64_read(&mm->pinned_vm);

	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

	locked = atomic64_add_return(nr_pages, &mm->pinned_vm);



	if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {

		atomic64_sub(nr_pages, &mm->pinned_vm);

		dev_err(scif_info.mdev.this_device,

			"locked(%lu) > lock_limit(%lu)\n",

			locked, lock_limit);

		return -ENOMEM;

	}

	atomic64_set(&mm->pinned_vm, locked);

	return 0;

}
@@ -326,7 +317,7 @@ int scif_destroy_window(struct scif_endpt *ep, struct scif_window *window) 


	might_sleep();

	if (!window->temp && window->mm) {

		__scif_dec_pinned_vm_lock(window->mm, window->nr_pages, 0);

		__scif_dec_pinned_vm_lock(window->mm, window->nr_pages);

		__scif_release_mm(window->mm);

		window->mm = NULL;

	}
@@ -737,7 +728,7 @@ done: 
					    ep->rma_info.dma_chan);

		} else {

			if (!__scif_dec_pinned_vm_lock(window->mm,

						       window->nr_pages, 1)) {

						       window->nr_pages)) {

				__scif_release_mm(window->mm);

				window->mm = NULL;

			}
@@ -1385,28 +1376,23 @@ int __scif_pin_pages(void *addr, size_t len, int *out_prot, 
		prot |= SCIF_PROT_WRITE;

retry:

		mm = current->mm;

		down_write(&mm->mmap_sem);

		if (ulimit) {

			err = __scif_check_inc_pinned_vm(mm, nr_pages);

			if (err) {

				up_write(&mm->mmap_sem);

				pinned_pages->nr_pages = 0;

				goto error_unmap;

			}

		}



		pinned_pages->nr_pages = get_user_pages(

		pinned_pages->nr_pages = get_user_pages_fast(

				(u64)addr,

				nr_pages,

				(prot & SCIF_PROT_WRITE) ? FOLL_WRITE : 0,

				pinned_pages->pages,

				NULL);

		up_write(&mm->mmap_sem);

				pinned_pages->pages);

		if (nr_pages != pinned_pages->nr_pages) {

			if (try_upgrade) {

				if (ulimit)

					__scif_dec_pinned_vm_lock(mm,

								  nr_pages, 0);

					__scif_dec_pinned_vm_lock(mm, nr_pages);

				/* Roll back any pinned pages */

				for (i = 0; i < pinned_pages->nr_pages; i++) {

					if (pinned_pages->pages[i])
@@ -1433,7 +1419,7 @@ retry: 
	return err;

dec_pinned:

	if (ulimit)

		__scif_dec_pinned_vm_lock(mm, nr_pages, 0);

		__scif_dec_pinned_vm_lock(mm, nr_pages);

	/* Something went wrong! Rollback */

error_unmap:

	pinned_pages->nr_pages = nr_pages;

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