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[75.142.250.213]) by smtp.gmail.com with ESMTPSA id e19sm10014698ioh.15.2021.01.10.13.58.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 Jan 2021 13:58:06 -0800 (PST) From: trix@redhat.com To: danil.kipnis@cloud.ionos.com, jinpu.wang@cloud.ionos.com, axboe@kernel.dk, natechancellor@gmail.com, ndesaulniers@google.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Tom Rix Subject: [PATCH] block/rnbd-clt: improve find_or_create_sess() return check Date: Sun, 10 Jan 2021 13:57:26 -0800 Message-Id: <20210110215726.861269-1-trix@redhat.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Tom Rix 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 Reviewed-by: Nathan Chancellor Acked-by: Jack Wang --- 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 96e3f9fe8241..251f747cf10d 100644 --- a/drivers/block/rnbd/rnbd-clt.c +++ b/drivers/block/rnbd/rnbd-clt.c @@ -919,6 +919,7 @@ 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) { @@ -934,8 +935,7 @@ 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; @@ -1203,13 +1203,11 @@ 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) {