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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: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
hifive-unleashed-5.1
Davidlohr Bueso 2019-02-06 09:59:16 -08:00 committed by Jason Gunthorpe
parent 70f8a3ca68
commit 4f564ff3d4
1 changed files with 11 additions and 25 deletions
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36
drivers/misc/mic/scif/scif_rma.c
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@ -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;