From: Michael (XIAO Xufeng) <xiaoxufeng@espressif.com>
Date: Fri, 31 May 2019 07:23:10 +0000 (+0800)
Subject: spi: fix a possible concurrency issue
X-Git-Tag: v3.3-rc~32^2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1d2a9efa55c9dfb9cf45e053760902d9fcc2aeec;p=esp-idf

spi: fix a possible concurrency issue
---

diff --git a/components/driver/spi_slave.c b/components/driver/spi_slave.c
index 02dd587df9..82fc99c10b 100644
--- a/components/driver/spi_slave.c
+++ b/components/driver/spi_slave.c
@@ -467,12 +467,14 @@ static void SPI_SLAVE_ISR_ATTR spi_intr(void *arg)
         }
     }
 
+    //Disable interrupt before checking to avoid concurrency issue.
+    esp_intr_disable(host->intr);
     //Grab next transaction
     r = xQueueReceiveFromISR(host->trans_queue, &trans, &do_yield);
-    if (!r) {
-        //No packet waiting. Disable interrupt.
-        esp_intr_disable(host->intr);
-    } else {
+    if (r) {
+        //enable the interrupt again if there is packet to send
+        esp_intr_enable(host->intr);
+
         //We have a transaction. Send it.
         host->hw->slave.trans_done = 0; //clear int bit
         host->cur_trans = trans;