hv: hv_fcopy: drop the obsolete message on transfer failure (d9b16529) · Commits · 戴 / test

drivers/hv/hv_fcopy.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -86,6 +86,18 @@ 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.
		*
		* NOTE: fcopy_read() happens to get the semaphore (very rare)? We're
		* still OK, because we've reported the failure to the host.
		*/
		if (down_trylock(&fcopy_transaction.read_sema))
		;

		}

		static int fcopy_handle_handshake(u32 version)
		@@ -344,6 +356,14 @@ static int fcopy_open(struct inode inode, struct file f)
		return 0;
		}

		/* XXX: there are still some tricky corner cases, e.g.,
		* 1) In a SMP guest, when fcopy_release() runs between
		* schedule_delayed_work() and fcopy_send_data(), there is
		* still a chance an obsolete message will be queued.
		*
		* 2) When the fcopy daemon is running, if we unload the driver,
		* we'll notice a kernel oops when we kill the daemon later.
		*/
		static int fcopy_release(struct inode inode, struct file f)
		{
		/*
		@@ -351,6 +371,13 @@ static int fcopy_release(struct inode inode, struct file f)
		*/
		in_hand_shake = true;
		opened = false;

		if (cancel_delayed_work_sync(&fcopy_work)) {
		/* We haven't up()-ed the semaphore(very rare)? */
		if (down_trylock(&fcopy_transaction.read_sema))
		;
		fcopy_respond_to_host(HV_E_FAIL);
		}
		return 0;
		}