Code implementing .receive_buf() callback can potentially call
serdev_device_write(), which will call serdev_device_poller(). We need
to make sure that such a call is a no-op in order to prevent
corrupting shared data buffer as well as breaking .receive_buf
callback that most likely does not expect that to happen.
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
---
common/serdev.c | 6 ++++++
include/serdev.h | 2 ++
2 files changed, 8 insertions(+)
diff --git a/common/serdev.c b/common/serdev.c
index 4a6dbefe6..3e0da0846 100644
--- a/common/serdev.c
+++ b/common/serdev.c
@@ -9,6 +9,10 @@ static void serdev_device_poller(void *context)
unsigned char *buf = serdev->buf;
int ret, len;
+ if (serdev->locked)
+ return;
+
+ serdev->locked = true;
/*
* Since this callback is a part of poller infrastructure we
* want to use _non_interruptible version of the function
@@ -37,6 +41,8 @@ static void serdev_device_poller(void *context)
} else {
poller_async_cancel(&serdev->poller);
}
+
+ serdev->locked = false;
}
static int serdev_device_set_polling_interval(struct param_d *param, void *serdev)
diff --git a/include/serdev.h b/include/serdev.h
index f5d34f527..29030538e 100644
--- a/include/serdev.h
+++ b/include/serdev.h
@@ -14,6 +14,7 @@
* @poller Async poller used to poll this serdev
* @polling_interval: Async poller periodicity
* @polling_window: Duration of a single busy loop poll
+ * @locked: Lock to prevent recursive polling
* @receive_buf: Function called with data received from device;
* returns number of bytes accepted;
*/
@@ -24,6 +25,7 @@ struct serdev_device {
struct poller_async poller;
uint64_t polling_interval;
uint64_t polling_window;
+ bool locked;
int (*receive_buf)(struct serdev_device *, const unsigned char *,
size_t);
--
2.21.0
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