In the case the user-space daemon crashes, hangs or is killed, we
need to down the semaphore, otherwise, after the daemon starts next
time, the obsolete data in fcopy_transaction.message or
fcopy_transaction.fcopy_msg will be used immediately.
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
---
v2: I removed the "FCP" prefix as Greg asked.
I also updated the output message a little:
"FCP: failed to acquire the semaphore" -->
"can not acquire the semaphore: it is benign"
drivers/hv/hv_fcopy.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index 23b2ce2..c518ad9 100644
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -86,6 +86,15 @@ static void fcopy_work_func(struct work_struct *dummy)
* process the pending transaction.
*/
fcopy_respond_to_host(HV_E_FAIL);
+
+ /* In the case the user-space daemon crashes, hangs or is killed, we
+ * need to down the semaphore, otherwise, after the daemon starts next
+ * time, the obsolete data in fcopy_transaction.message or
+ * fcopy_transaction.fcopy_msg will be used immediately.
+ */
+ if (down_trylock(&fcopy_transaction.read_sema))
+ pr_debug("can not acquire the semaphore: it is benign\n");
+
}
static int fcopy_handle_handshake(u32 version)
--
1.9.1
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