[PATCH 5.4 201/408] RDMA/ucma: Fix locking for ctx->events_reported

Greg Kroah-Hartman
2020-10-27T14:37:40Z

From: Jason Gunthorpe <jgg@nvidia.com>

[ Upstream commit 98837c6c3d7285f6eca86480b6f7fac6880e27a8 ]

This value is locked under the file->mut, ensure it is held whenever
touching it.

The case in ucma_migrate_id() is a race, while in ucma_free_uctx() it is
already not possible for the write side to run, the movement is just for
clarity.

Fixes: 88314e4dda1e ("RDMA/cma: add support for rdma_migrate_id()")
Link: https://lore.kernel.org/r/20200818120526.702120-10-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/infiniband/core/ucma.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index f4f79f1292b91..d7c74f095805a 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -581,6 +581,7 @@ static int ucma_free_ctx(struct ucma_context *ctx)
list_move_tail(&uevent->list, &list);
}
list_del(&ctx->list);
+ events_reported = ctx->events_reported;
mutex_unlock(&ctx->file->mut);

list_for_each_entry_safe(uevent, tmp, &list, list) {
@@ -590,7 +591,6 @@ static int ucma_free_ctx(struct ucma_context *ctx)
kfree(uevent);
}

- events_reported = ctx->events_reported;
mutex_destroy(&ctx->mutex);
kfree(ctx);
return events_reported;
@@ -1639,7 +1639,9 @@ static ssize_t ucma_migrate_id(struct ucma_file *new_file,

cur_file = ctx->file;
if (cur_file == new_file) {
+ mutex_lock(&cur_file->mut);
resp.events_reported = ctx->events_reported;
+ mutex_unlock(&cur_file->mut);
goto response;
}

--
2.25.1