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authorAlexander Usyskin <alexander.usyskin@intel.com>2021-08-01 09:25:32 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-08-01 09:54:22 +0200
commit0fc7ca624b1452050d31b05cd198e38a1b74d1b3 (patch)
treebe3a9ff0507896520bbebbcc20a63ca6390ad584
parentpps: clients: parport: Switch to use module_parport_driver() (diff)
downloadlinux-0fc7ca624b1452050d31b05cd198e38a1b74d1b3.tar.xz
linux-0fc7ca624b1452050d31b05cd198e38a1b74d1b3.zip
samples: mei: don't wait on read completion upon write.
The original mei driver communication was strictly write command and receive response flow, the completion of write was determined when response was ready using select(). This paradigm is a long time not true. There can be write without a response and an unsolicited read. The driver is capable of handling those. Adjust also the sample code and remove select() on read() from the write flow. Add select to the read flow to showcase how to do the read with a timeout. Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> Link: https://lore.kernel.org/r/20210801072532.8668-1-tomas.winkler@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--samples/mei/mei-amt-version.c51
1 files changed, 30 insertions, 21 deletions
diff --git a/samples/mei/mei-amt-version.c b/samples/mei/mei-amt-version.c
index ad3e56042f96..867debd3b912 100644
--- a/samples/mei/mei-amt-version.c
+++ b/samples/mei/mei-amt-version.c
@@ -154,31 +154,52 @@ err:
static ssize_t mei_recv_msg(struct mei *me, unsigned char *buffer,
ssize_t len, unsigned long timeout)
{
+ struct timeval tv;
+ fd_set set;
ssize_t rc;
+ tv.tv_sec = timeout / 1000;
+ tv.tv_usec = (timeout % 1000) * 1000000;
+
mei_msg(me, "call read length = %zd\n", len);
+ FD_ZERO(&set);
+ FD_SET(me->fd, &set);
+ rc = select(me->fd + 1, &set, NULL, NULL, &tv);
+ if (rc > 0 && FD_ISSET(me->fd, &set)) {
+ mei_msg(me, "have reply\n");
+ } else if (rc == 0) {
+ rc = -1;
+ mei_err(me, "read failed on timeout\n");
+ goto out;
+ } else { /* rc < 0 */
+ rc = errno;
+ mei_err(me, "read failed on select with status %zd %s\n",
+ rc, strerror(errno));
+ goto out;
+ }
+
rc = read(me->fd, buffer, len);
if (rc < 0) {
mei_err(me, "read failed with status %zd %s\n",
rc, strerror(errno));
- mei_deinit(me);
- } else {
- mei_msg(me, "read succeeded with result %zd\n", rc);
+ goto out;
}
+
+ mei_msg(me, "read succeeded with result %zd\n", rc);
+
+out:
+ if (rc < 0)
+ mei_deinit(me);
+
return rc;
}
static ssize_t mei_send_msg(struct mei *me, const unsigned char *buffer,
ssize_t len, unsigned long timeout)
{
- struct timeval tv;
ssize_t written;
ssize_t rc;
- fd_set set;
-
- tv.tv_sec = timeout / 1000;
- tv.tv_usec = (timeout % 1000) * 1000000;
mei_msg(me, "call write length = %zd\n", len);
@@ -189,19 +210,7 @@ static ssize_t mei_send_msg(struct mei *me, const unsigned char *buffer,
written, strerror(errno));
goto out;
}
-
- FD_ZERO(&set);
- FD_SET(me->fd, &set);
- rc = select(me->fd + 1 , &set, NULL, NULL, &tv);
- if (rc > 0 && FD_ISSET(me->fd, &set)) {
- mei_msg(me, "write success\n");
- } else if (rc == 0) {
- mei_err(me, "write failed on timeout with status\n");
- goto out;
- } else { /* rc < 0 */
- mei_err(me, "write failed on select with status %zd\n", rc);
- goto out;
- }
+ mei_msg(me, "write success\n");
rc = written;
out: