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Subject[PATCH] block/rnbd-clt: improve find_or_create_sess() return check
Date
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>
---
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) {
--
2.27.0
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