linux-kernel - [PATCH v2 01/13] staging: lustre: kg_sem semaphore handling is incorrectly

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Date:	Wed, 23 Dec 2015 16:24:40 -0500
From:	James Simmons <jsimmons@...radead.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devel@...verdev.osuosl.org, Oleg Drokin <oleg.drokin@...el.com>,
	Andreas Dilger <andreas.dilger@...el.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	lustre-devel@...ts.lustre.org,
	James Simmons <jsimmons@...radead.org>
Subject: [PATCH v2 01/13] staging: lustre: kg_sem semaphore handling is incorrectly

During the removal of the cfs wrappers the kg_sem semaphore
was handled incorrectly. We need to take a write lock when
writing data to the kkuc_groups. The libcfs_kkuc_group_foreach
needs to only take a read lock. This makes use match the
OpenSFS development branch.

Signed-off-by: James Simmons <jsimmons@...radead.org>
---
 .../lustre/lustre/libcfs/kernel_user_comm.c        |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c b/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
index d8230ae..1a052ac 100644
--- a/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
+++ b/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
@@ -186,7 +186,7 @@ int libcfs_kkuc_group_put(int group, void *payload)
 	int		 rc = 0;
 	int one_success = 0;
 
-	down_read(&kg_sem);
+	down_write(&kg_sem);
 	list_for_each_entry(reg, &kkuc_groups[group], kr_chain) {
 		if (reg->kr_fp != NULL) {
 			rc = libcfs_kkuc_msg_put(reg->kr_fp, payload);
@@ -198,7 +198,7 @@ int libcfs_kkuc_group_put(int group, void *payload)
 			}
 		}
 	}
-	up_read(&kg_sem);
+	up_write(&kg_sem);
 
 	/* don't return an error if the message has been delivered
 	 * at least to one agent */
@@ -230,12 +230,12 @@ int libcfs_kkuc_group_foreach(int group, libcfs_kkuc_cb_t cb_func,
 	if (kkuc_groups[group].next == NULL)
 		return 0;
 
-	down_write(&kg_sem);
+	down_read(&kg_sem);
 	list_for_each_entry(reg, &kkuc_groups[group], kr_chain) {
 		if (reg->kr_fp != NULL)
 			rc = cb_func(reg->kr_data, cb_arg);
 	}
-	up_write(&kg_sem);
+	up_read(&kg_sem);
 
 	return rc;
 }
-- 
1.7.1

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