[Xen-devel] [PATCH v3] xen/scsiback: add error handling for xenbus_printf

[Zhouyang Jia <jiazhouyang09@xxxxxxxxx>]

When xenbus_printf fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling xenbus_printf.

Signed-off-by: Zhouyang Jia <jiazhouyang09@xxxxxxxxx>
---
v1->v2:
- Use xenbus_dev_error to report errors.
v2->v3:
- Fix compilation errors.
---
 drivers/xen/xen-scsiback.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index 7bc88fd..e2f3e8b 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -1012,6 +1012,7 @@ static void scsiback_do_add_lun(struct vscsibk_info 
*info, const char *state,
 {
        struct v2p_entry *entry;
        unsigned long flags;
+       int err;
 
        if (try) {
                spin_lock_irqsave(&info->v2p_lock, flags);
@@ -1027,8 +1028,11 @@ static void scsiback_do_add_lun(struct vscsibk_info 
*info, const char *state,
                        scsiback_del_translation_entry(info, vir);
                }
        } else if (!try) {
-               xenbus_printf(XBT_NIL, info->dev->nodename, state,
+               err = xenbus_printf(XBT_NIL, info->dev->nodename, state,
                              "%d", XenbusStateClosed);
+               if (err)
+                       xenbus_dev_error(info->dev, err,
+                               "%s: writing %s", __func__, state);
        }
 }
 
@@ -1067,8 +1071,11 @@ static void scsiback_do_1lun_hotplug(struct vscsibk_info 
*info, int op,
        snprintf(str, sizeof(str), "vscsi-devs/%s/p-dev", ent);
        val = xenbus_read(XBT_NIL, dev->nodename, str, NULL);
        if (IS_ERR(val)) {
-               xenbus_printf(XBT_NIL, dev->nodename, state,
+               err = xenbus_printf(XBT_NIL, dev->nodename, state,
                              "%d", XenbusStateClosed);
+               if (err)
+                       xenbus_dev_error(info->dev, err,
+                               "%s: writing %s", __func__, state);
                return;
        }
        strlcpy(phy, val, VSCSI_NAMELEN);
@@ -1079,8 +1086,11 @@ static void scsiback_do_1lun_hotplug(struct vscsibk_info 
*info, int op,
        err = xenbus_scanf(XBT_NIL, dev->nodename, str, "%u:%u:%u:%u",
                           &vir.hst, &vir.chn, &vir.tgt, &vir.lun);
        if (XENBUS_EXIST_ERR(err)) {
-               xenbus_printf(XBT_NIL, dev->nodename, state,
+               err = xenbus_printf(XBT_NIL, dev->nodename, state,
                              "%d", XenbusStateClosed);
+               if (err)
+                       xenbus_dev_error(info->dev, err,
+                               "%s: writing %s", __func__, state);
                return;
        }
 
-- 
2.7.4


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