All of lore.kernel.org
 help / color / mirror / Atom feed
From: Bob Pearson <rpearsonhpe@gmail.com>
To: jgg@nvidia.com, zyjzyj2000@gmail.com, linux-rdma@vger.kernel.org
Cc: Bob Pearson <rpearsonhpe@gmail.com>
Subject: [PATCH for-next v4 13/13] RDMA/rxe: Protect against race between get_index and drop_ref
Date: Wed,  3 Nov 2021 00:02:42 -0500	[thread overview]
Message-ID: <20211103050241.61293-14-rpearsonhpe@gmail.com> (raw)
In-Reply-To: <20211103050241.61293-1-rpearsonhpe@gmail.com>

Use refcount_inc_not_zero instead of kref_get to protect object
pointer returned by rxe_pool_get_index() to prevent chance of a
race between get_index and drop_ref by another thread.

Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
---
 drivers/infiniband/sw/rxe/rxe_pool.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c
index 863fa62da077..688944fa3926 100644
--- a/drivers/infiniband/sw/rxe/rxe_pool.c
+++ b/drivers/infiniband/sw/rxe/rxe_pool.c
@@ -272,8 +272,13 @@ void *rxe_pool_get_index(struct rxe_pool *pool, unsigned long index)
 	}
 
 	elem = xa_load(&pool->xarray.xa, index);
+
 	if (elem) {
-		kref_get(&elem->ref_cnt);
+		/* protect against a race with someone else dropping
+		 * the last reference to the object
+		 */
+		if (!__rxe_add_ref(elem))
+			return NULL;
 		obj = elem->obj;
 	} else {
 		obj = NULL;
-- 
2.30.2


  parent reply	other threads:[~2021-11-03  5:03 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-03  5:02 [PATCH for-next v4 00/13] Correct race conditions in rdma_rxe Bob Pearson
2021-11-03  5:02 ` [PATCH for-next v4 01/13] RDMA/rxe: Replace irqsave locks with bh locks Bob Pearson
2021-11-03  5:02 ` [PATCH for-next v4 02/13] RDMA/rxe: Cleanup rxe_pool_entry Bob Pearson
2021-11-03  5:02 ` [PATCH for-next v4 03/13] RDMA/rxe: Copy setup parameters into rxe_pool Bob Pearson
2021-11-03  5:02 ` [PATCH for-next v4 04/13] RDMA/rxe: Save object pointer in pool element Bob Pearson
2021-11-03  5:02 ` [PATCH for-next v4 05/13] RDMA/rxe: Replace RB tree by xarray for indexes Bob Pearson
2021-11-19 17:38   ` Jason Gunthorpe
2021-11-03  5:02 ` [PATCH for-next v4 06/13] RDMA/rxe: Remove #include "rxe_loc.h" from rxe_pool.c Bob Pearson
2021-11-03  5:02 ` [PATCH v4 for-next 07/13] RDMA/rxe: Remove some #defines from rxe_pool.h Bob Pearson
2021-11-03  5:02 ` [PATCH v4 for-next 08/13] RDMA/rxe: Reverse the sense of RXE_POOL_NO_ALLOC Bob Pearson
2021-11-03  5:02 ` [PATCH for-next v4 09/13] RDMA/rxe: Replaced keyed rxe objects by indexed objects Bob Pearson
2021-11-19 17:41   ` Jason Gunthorpe
2021-11-30 19:35     ` Bob Pearson
2021-12-02  7:14       ` Christoph Lameter
2021-11-03  5:02 ` [PATCH for-next v4 10/13] RDMA/rxe: Prevent taking references to dead objects Bob Pearson
2021-11-19 17:45   ` Jason Gunthorpe
2021-11-30 20:05     ` Bob Pearson
2021-12-01 13:55       ` Jason Gunthorpe
2021-11-03  5:02 ` [PATCH for-next v4 11/13] RDMA/rxe: Fix ref error in rxe_av.c Bob Pearson
2021-11-03  5:02 ` [PATCH for-next v4 12/13] RDMA/rxe: Replace mr by rkey in responder resources Bob Pearson
2021-11-03  5:02 ` Bob Pearson [this message]
2021-11-19 17:46   ` [PATCH for-next v4 13/13] RDMA/rxe: Protect against race between get_index and drop_ref Jason Gunthorpe
2021-11-19 17:59 ` [PATCH for-next v4 00/13] Correct race conditions in rdma_rxe Jason Gunthorpe

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20211103050241.61293-14-rpearsonhpe@gmail.com \
    --to=rpearsonhpe@gmail.com \
    --cc=jgg@nvidia.com \
    --cc=linux-rdma@vger.kernel.org \
    --cc=zyjzyj2000@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.