From 6188675b72990ee3f76b465e6020b38792604130 Mon Sep 17 00:00:00 2001
From: Frank Stettner <frank-stettner@gmx.net>
Date: Thu, 11 Apr 2019 14:33:19 +0200
Subject: [PATCH] scpi_libgpib: Add mutex to SPoll.

---
 src/scpi/scpi_libgpib.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/scpi/scpi_libgpib.c b/src/scpi/scpi_libgpib.c
index 26fcadac..5c82bd6f 100644
--- a/src/scpi/scpi_libgpib.c
+++ b/src/scpi/scpi_libgpib.c
@@ -169,13 +169,16 @@ SR_PRIV int sr_scpi_gpib_spoll(struct sr_scpi_dev_inst *scpi, char *buf)
 {
 	struct scpi_gpib *gscpi = scpi->priv;
 
+	g_mutex_lock(&scpi->scpi_mutex);
 	ibrsp(gscpi->descriptor, buf);
 
 	if (ibsta & ERR) {
 		sr_err("Error while serial polling: iberr = %s.",
 			gpib_error_string(iberr));
+		g_mutex_unlock(&scpi->scpi_mutex);
 		return SR_ERR;
 	}
+	g_mutex_unlock(&scpi->scpi_mutex);
 	sr_spew("Successful serial poll: 0x%x", (uint8_t)buf[0]);
 
 	return SR_OK;