[PATCH 10/22] mm/hmm: Remove duplicate condition test before wait_event_timeout

Christoph Hellwig
2019-07-01T06:21:52Z

From: Jason Gunthorpe <jgg@mellanox.com>

The wait_event_timeout macro already tests the condition as its first
action, so there is no reason to open code another version of this, all
that does is skip the might_sleep() debugging in common cases, which is
not helpful.

Further, based on prior patches, we can now simplify the required condition
test:
- If range is valid memory then so is range->hmm
- If hmm_release() has run then range->valid is set to false
at the same time as dead, so no reason to check both.
- A valid hmm has a valid hmm->mm.

Allowing the return value of wait_event_timeout() (along with its internal
barriers) to compute the result of the function.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Philip Yang <Philip.Yang@amd.com>
---
include/linux/hmm.h | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 1d97b6d62c5b..26e7c477490c 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -209,17 +209,8 @@ static inline unsigned long hmm_range_page_size(const struct hmm_range *range)
static inline bool hmm_range_wait_until_valid(struct hmm_range *range,
unsigned long timeout)
{
- /* Check if mm is dead ? */
- if (range->hmm == NULL || range->hmm->dead || range->hmm->mm == NULL) {
- range->valid = false;
- return false;
- }
- if (range->valid)
- return true;
- wait_event_timeout(range->hmm->wq, range->valid || range->hmm->dead,
- msecs_to_jiffies(timeout));
- /* Return current valid status just in case we get lucky */
- return range->valid;
+ return wait_event_timeout(range->hmm->wq, range->valid,
+ msecs_to_jiffies(timeout)) != 0;
}

/*
--
2.20.1