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From: Gioh Kim <gi-oh.kim@ionos.com>
To: linux-block@vger.kernel.org, linux-doc@vger.kernel.org
Cc: axboe@kernel.dk, akinobu.mita@gmail.com, corbet@lwn.net,
	hch@infradead.org, sagi@grimberg.me, bvanassche@acm.org,
	haris.iqbal@ionos.com, jinpu.wang@ionos.com,
	Tom Rix <trix@redhat.com>, Gioh Kim <gi-oh.kim@ionos.com>
Subject: [PATCHv5 for-next 11/19] block/rnbd-clt: Improve find_or_create_sess() return check
Date: Mon, 19 Apr 2021 09:37:14 +0200
Message-ID: <20210419073722.15351-12-gi-oh.kim@ionos.com> (raw)
In-Reply-To: <20210419073722.15351-1-gi-oh.kim@ionos.com>

From: Tom Rix <trix@redhat.com>

clang static analysis reports this problem

rnbd-clt.c:1212:11: warning: Branch condition evaluates to a
  garbage value
        else if (!first)
                 ^~~~~~

This is triggered in the find_and_get_or_create_sess() call
because the variable first is not initialized and the
earlier check is specifically for

	if (sess == ERR_PTR(-ENOMEM))

This is false positive.

But the if-check can be reduced by initializing first to
false and then returning if the call to find_or_creat_sess()
does not set it to true.  When it remains false, either
sess will be valid or not.  The not case is caught by
find_and_get_or_create_sess()'s caller rnbd_clt_map_device()

	sess = find_and_get_or_create_sess(...);
	if (IS_ERR(sess))
		return ERR_CAST(sess);

Since find_and_get_or_create_sess() initializes first to false
setting it in find_or_create_sess() is not needed.

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
---
 drivers/block/rnbd/rnbd-clt.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
index 652b41cc4492..9b44aac680d5 100644
--- a/drivers/block/rnbd/rnbd-clt.c
+++ b/drivers/block/rnbd/rnbd-clt.c
@@ -910,6 +910,7 @@ static struct rnbd_clt_session *__find_and_get_sess(const char *sessname)
 	return NULL;
 }
 
+/* caller is responsible for initializing 'first' to false */
 static struct
 rnbd_clt_session *find_or_create_sess(const char *sessname, bool *first)
 {
@@ -925,8 +926,7 @@ rnbd_clt_session *find_or_create_sess(const char *sessname, bool *first)
 		}
 		list_add(&sess->list, &sess_list);
 		*first = true;
-	} else
-		*first = false;
+	}
 	mutex_unlock(&sess_lock);
 
 	return sess;
@@ -1194,13 +1194,11 @@ find_and_get_or_create_sess(const char *sessname,
 	struct rnbd_clt_session *sess;
 	struct rtrs_attrs attrs;
 	int err;
-	bool first;
+	bool first = false;
 	struct rtrs_clt_ops rtrs_ops;
 
 	sess = find_or_create_sess(sessname, &first);
-	if (sess == ERR_PTR(-ENOMEM))
-		return ERR_PTR(-ENOMEM);
-	else if (!first)
+	if (!first)
 		return sess;
 
 	if (!path_cnt) {
-- 
2.25.1


  parent reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19  7:37 [PATCHv5 for-next 00/19] Misc update for rnbd Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 01/19] MAINTAINERS: Change maintainer for rnbd module Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 02/19] Documentation/sysfs-block-rnbd: Add descriptions for remap_device and resize Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 03/19] block/rnbd-clt: Remove some arguments from insert_dev_if_not_exists_devpath Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 04/19] block/rnbd-clt: Remove some arguments from rnbd_client_setup_device Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 05/19] block/rnbd-clt: Move add_disk(dev->gd) to rnbd_clt_setup_gen_disk Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 06/19] block/rnbd: Kill rnbd_clt_destroy_default_group Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 07/19] block/rnbd: Kill destroy_device_cb Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 08/19] block/rnbd-clt: Replace {NO_WAIT,WAIT} with RTRS_PERMIT_{WAIT,NOWAIT} Gioh Kim
2021-04-19  7:46   ` Leon Romanovsky
2021-04-19  7:37 ` [PATCHv5 for-next 09/19] block/rnbd-srv: Prevent a deadlock generated by accessing sysfs in parallel Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 10/19] block/rnbd-srv: Remove force_close file after holding a lock Gioh Kim
2021-04-19  7:37 ` Gioh Kim [this message]
2021-04-19  7:37 ` [PATCHv5 for-next 12/19] block/rnbd-clt: Fix missing a memory free when unloading the module Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 13/19] block/rnbd-clt: Support polling mode for IO latency optimization Gioh Kim
2021-04-19  7:47   ` Leon Romanovsky
2021-04-19  7:37 ` [PATCHv5 for-next 14/19] Documentation/ABI/rnbd-clt: Add description for nr_poll_queues Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 15/19] block/rnbd-srv: Remove unused arguments of rnbd_srv_rdma_ev Gioh Kim
2021-04-19  7:47   ` Leon Romanovsky
2021-04-19  7:37 ` [PATCHv5 for-next 16/19] block/rnbd-clt: Generate kobject_uevent when the rnbd device state changes Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 17/19] block/rnbd-clt: Remove max_segment_size Gioh Kim
2021-04-19  7:47   ` Leon Romanovsky
2021-04-19  7:37 ` [PATCHv5 for-next 18/19] block/rnbd-clt-sysfs: Remove copy buffer overlap in rnbd_clt_get_path_name Gioh Kim
2021-04-19  7:37 ` [PATCHv5 for-next 19/19] block/rnbd: Use strscpy instead of strlcpy Gioh Kim
2021-04-19 17:54 ` [PATCHv5 for-next 00/19] Misc update for rnbd Jens Axboe

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