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RDMA/ucma: Do not use file->mut to lock destroying 

The only reader of destroying is inside a handler under the handler_mutex,
so directly use the handler_mutex when setting it instead of the larger
file->mut.

As the refcount could be zero here, and the cm_id already freed, and
additional refcount grab around the locking is required to touch the
cm_id.

Link: https://lore.kernel.org/r/20200818120526.702120-8-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Jason Gunthorpe 2020-08-18 15:05:19 +03:00
parent d114c6feed
commit 308571debc
1 changed files with 11 additions and 3 deletions
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14
drivers/infiniband/core/ucma.c
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@ -602,9 +602,17 @@ static int ucma_free_ctx(struct ucma_context *ctx)
static int __destroy_id(struct ucma_context *ctx)
{
mutex_lock(&ctx->file->mut);
ctx->destroying = 1;
mutex_unlock(&ctx->file->mut);
/*
* If the refcount is already 0 then ucma_close_id() has already
* destroyed the cm_id, otherwise holding the refcount keeps cm_id
* valid. Prevent queue_work() from being called.
*/
if (refcount_inc_not_zero(&ctx->ref)) {
rdma_lock_handler(ctx->cm_id);
ctx->destroying = 1;
rdma_unlock_handler(ctx->cm_id);
ucma_put_ctx(ctx);
}
flush_workqueue(ctx->file->close_wq);
/* At this point it's guaranteed that there is no inflight closing task */