rpmsg: char: treat rpmsg_trysend() ENOMEM as EAGAIN

rpmsg_trysend() returns -ENOMEM when no rpmsg buffer can be allocated.
this causes write to fail with this error as opposed to -EAGAIN.
this is what user space applications (and libraries like boost.asio)
would expect when using normal character devices.

Signed-off-by: Tim Blechmann <tim@klingt.org>
Cc: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220313024541.1579848-2-tim@klingt.org

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 5663cf7..434dc8a 100644 (file)
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -242,10 +242,13 @@ static ssize_t rpmsg_eptdev_write_iter(struct kiocb *iocb,
                goto unlock_eptdev;
        }
 
-       if (filp->f_flags & O_NONBLOCK)
+       if (filp->f_flags & O_NONBLOCK) {
                ret = rpmsg_trysendto(eptdev->ept, kbuf, len, eptdev->chinfo.dst);
-       else
+               if (ret == -ENOMEM)
+                       ret = -EAGAIN;
+       } else {
                ret = rpmsg_sendto(eptdev->ept, kbuf, len, eptdev->chinfo.dst);
+       }
 
 unlock_eptdev:
        mutex_unlock(&eptdev->ept_lock);