[Qemu-devel] [PATCH][RESEND] char: Flush read buffer in mux_chr_can_read

[Qemu-devel] [PATCH][RESEND] char: Flush read buffer in mux_chr_can_read

[Jan Kiszka]

From: Jan Kiszka <jan.kiszka@siemens.com>

Move the buffer flush from mux_chr_read to mux_chr_can_read. While the
latter is called periodically, the former will only be invoked when new
characters arrive at the back-end. This caused problems to front-end
drivers whenever they were unable to read data immediately, e.g.
virtio-console attached to stdio.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

While this may not solve all problems on s390, it does improve the
muxed virtio console for x86 guest and still looks correct to me.

 qemu-char.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index faaf624..00ded76 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -404,6 +404,8 @@ static int mux_chr_can_read(void *opaque)
     MuxDriver *d = chr->opaque;
     int m = d->focus;
 
+    mux_chr_accept_input(opaque);
+
     if ((d->prod[m] - d->cons[m]) < MUX_BUFFER_SIZE)
         return 1;
     if (d->chr_can_read[m])
@@ -418,8 +420,6 @@ static void mux_chr_read(void *opaque, const uint8_t *buf, int size)
     int m = d->focus;
     int i;
 
-    mux_chr_accept_input (opaque);
-
     for(i = 0; i < size; i++)
         if (mux_proc_byte(chr, d, buf[i])) {
             if (d->prod[m] == d->cons[m] &&
-- 
1.6.0.2

[Qemu-devel] [PATCH][RESEND] char: Flush read buffer in mux_chr_can_read

[Jan Kiszka]

Move the buffer flush from mux_chr_read to mux_chr_can_read. While the
latter is called periodically, the former will only be invoked when new
characters arrive at the back-end. This caused problems to front-end
drivers whenever they were unable to read data immediately, e.g.
virtio-console attached to stdio.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 qemu-char.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index 6d2dce7..f4c3876 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -398,6 +398,8 @@ static int mux_chr_can_read(void *opaque)
     MuxDriver *d = chr->opaque;
     int m = d->focus;
 
+    mux_chr_accept_input(opaque);
+
     if ((d->prod[m] - d->cons[m]) < MUX_BUFFER_SIZE)
         return 1;
     if (d->chr_can_read[m])
@@ -412,8 +414,6 @@ static void mux_chr_read(void *opaque, const uint8_t *buf, int size)
     int m = d->focus;
     int i;
 
-    mux_chr_accept_input (opaque);
-
     for(i = 0; i < size; i++)
         if (mux_proc_byte(chr, d, buf[i])) {
             if (d->prod[m] == d->cons[m] &&
-- 
1.7.1