[PATCH v3] scsi: ibmvscsi: Don't use rc uninitialized in ibmvscsi_do_work

[Nathan Chancellor]

clang warns:

drivers/scsi/ibmvscsi/ibmvscsi.c:2126:7: warning: variable 'rc' is used
uninitialized whenever switch case is taken [-Wsometimes-uninitialized]
        case IBMVSCSI_HOST_ACTION_NONE:
             ^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/scsi/ibmvscsi/ibmvscsi.c:2151:6: note: uninitialized use occurs
here
        if (rc) {
            ^~

Initialize rc in the IBMVSCSI_HOST_ACTION_UNBLOCK case statement then
shuffle IBMVSCSI_HOST_ACTION_NONE down to the default case statement and
make it return early so that rc is never used uninitialized in this
function.

Fixes: 035a3c4046b5 ("scsi: ibmvscsi: redo driver work thread to use enum 
action states")
Link: https://github.com/ClangBuiltLinux/linux/issues/502
Suggested-by: Michael Ellerman <m...@ellerman.id.au>
Suggested-by: Tyrel Datwyler <tyr...@linux.ibm.com>
Signed-off-by: Nathan Chancellor <natechancel...@gmail.com>
---

v1 -> v2:

* Initialize rc in the case statements, rather than at the top of the
  function, as suggested by Michael.
  
v2 -> v3:

* default and IBMVSCSI_HOST_ACTION_NONE now return early from the
  function, as requested by Tyrel.

 drivers/scsi/ibmvscsi/ibmvscsi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 65053daef5f7..7f66a7783209 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -2109,8 +2109,8 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data 
*hostdata)
 
        spin_lock_irqsave(hostdata->host->host_lock, flags);
        switch (hostdata->action) {
-       case IBMVSCSI_HOST_ACTION_NONE:
        case IBMVSCSI_HOST_ACTION_UNBLOCK:
+               rc = 0;
                break;
        case IBMVSCSI_HOST_ACTION_RESET:
                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
@@ -2128,8 +2128,10 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data 
*hostdata)
                if (!rc)
                        rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 
0);
                break;
+       case IBMVSCSI_HOST_ACTION_NONE:
        default:
-               break;
+               spin_unlock_irqrestore(hostdata->host->host_lock, flags);
+               return;
        }
 
        hostdata->action = IBMVSCSI_HOST_ACTION_NONE;
-- 
2.22.0.rc3