From 07e266a7753d952978f317aa2b206b4da4769567 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Tue, 18 Aug 2020 15:05:14 +0300 Subject: [PATCH] RDMA/ucma: Remove unnecessary locking of file->ctx_list in close During the file_operations release function it is already not possible that write() can be running concurrently, remove the extra locking around the ctx_list. Link: https://lore.kernel.org/r/20200818120526.702120-3-leon@kernel.org Signed-off-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/ucma.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index 625168563443..9b019f31743d 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -1824,12 +1824,17 @@ static int ucma_close(struct inode *inode, struct file *filp) struct ucma_file *file = filp->private_data; struct ucma_context *ctx, *tmp; - mutex_lock(&file->mut); + /* + * ctx_list can only be mutated under the write(), which is no longer + * possible, so no locking needed. + */ list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) { + xa_erase(&ctx_table, ctx->id); + + mutex_lock(&file->mut); ctx->destroying = 1; mutex_unlock(&file->mut); - xa_erase(&ctx_table, ctx->id); flush_workqueue(file->close_wq); /* At that step once ctx was marked as destroying and workqueue * was flushed we are safe from any inflights handlers that @@ -1849,9 +1854,7 @@ static int ucma_close(struct inode *inode, struct file *filp) } ucma_free_ctx(ctx); - mutex_lock(&file->mut); } - mutex_unlock(&file->mut); destroy_workqueue(file->close_wq); kfree(file); return 0;