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[PULL 65/92] char: fix logging when chardev write fails
From: |
Paolo Bonzini |
Subject: |
[PULL 65/92] char: fix logging when chardev write fails |
Date: |
Thu, 24 Sep 2020 05:22:47 -0400 |
From: Daniel P. Berrangé <berrange@redhat.com>
The qemu_chr_write_buffer() method sends data to the chardev backend for
writing, and then also writes to the log file. In case the chardev
backend only writes part of the data buffer, we need to make sure we
only log the same subset. qemu_chr_write_buffer() will be invoked again
later to write the rest of the buffer.
In the case the chardev backend returns an error though, no further
attempts to likely to be made to write the data. We must therefore write
the entire buffer to the log immediately.
An example where this is important is with the socket backend. This will
return -1 for all writes if no client is currently connected. We still
wish to write data to the log file when no client is present though.
This used to work because the chardev would return "len" to pretend it
had written all data when no client is connected, but this changed to
return an error in
commit 271094474b65de1ad7aaf729938de3d9b9d0d36f
Author: Dima Stepanov <dimastep@yandex-team.ru>
Date: Thu May 28 12:11:18 2020 +0300
char-socket: return -1 in case of disconnect during tcp_chr_write
and this broke the logging, resulting in all data being discarded when
no client is present.
Fixes: https://bugs.launchpad.net/qemu/+bug/1893691
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
chardev/char.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/chardev/char.c b/chardev/char.c
index 6b85099c03..78553125d3 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -138,7 +138,20 @@ static int qemu_chr_write_buffer(Chardev *s,
}
}
if (*offset > 0) {
+ /*
+ * If some data was written by backend, we should
+ * only log what was actually written. This method
+ * may be invoked again to write the remaining
+ * method, thus we'll log the remainder at that time.
+ */
qemu_chr_write_log(s, buf, *offset);
+ } else if (res < 0) {
+ /*
+ * If a fatal error was reported by the backend,
+ * assume this method won't be invoked again with
+ * this buffer, so log it all right away.
+ */
+ qemu_chr_write_log(s, buf, len);
}
qemu_mutex_unlock(&s->chr_write_lock);
--
2.26.2
- [PULL 54/92] checkpatch: avoid error on cover letter files, (continued)
- [PULL 54/92] checkpatch: avoid error on cover letter files, Paolo Bonzini, 2020/09/24
- [PULL 58/92] tests/tcg: reinstate or replace desired parts of rules.mak, Paolo Bonzini, 2020/09/24
- [PULL 57/92] oss-fuzz: move linker arg to fix coverage-build, Paolo Bonzini, 2020/09/24
- [PULL 56/92] configure: fix performance regression due to PIC objects, Paolo Bonzini, 2020/09/24
- [PULL 63/92] smp: drop support for deprecated (invalid topologies), Paolo Bonzini, 2020/09/24
- [PULL 59/92] configure: cleanup invocation of submodule Make, Paolo Bonzini, 2020/09/24
- [PULL 61/92] configure: do not clobber environment CFLAGS/CXXFLAGS/LDFLAGS, Paolo Bonzini, 2020/09/24
- [PULL 62/92] configure: consistently pass CFLAGS/CXXFLAGS/LDFLAGS to meson, Paolo Bonzini, 2020/09/24
- [PULL 60/92] configure: cleanup CFLAGS and LDFLAGS for submodules, Paolo Bonzini, 2020/09/24
- [PULL 64/92] cphp: remove deprecated cpu-add command(s), Paolo Bonzini, 2020/09/24
- [PULL 65/92] char: fix logging when chardev write fails,
Paolo Bonzini <=
- [PULL 66/92] qom: Document all function parameters in doc comments, Paolo Bonzini, 2020/09/24
- [PULL 67/92] qom: Use kernel-doc private/public tags in structs, Paolo Bonzini, 2020/09/24
- [PULL 68/92] qom: Use ``code`` Sphinx syntax where appropriate, Paolo Bonzini, 2020/09/24
- [PULL 69/92] qom: Add kernel-doc markup to introduction doc comment, Paolo Bonzini, 2020/09/24
- [PULL 70/92] qom: Reformat section titles using Sphinx syntax, Paolo Bonzini, 2020/09/24
- [PULL 71/92] qom: Indent existing code examples, Paolo Bonzini, 2020/09/24
- [PULL 72/92] qom: Add code block markup to all code blocks, Paolo Bonzini, 2020/09/24
- [PULL 73/92] docs: Create docs/devel/qom.rst, Paolo Bonzini, 2020/09/24
- [PULL 74/92] docs: Move object.h overview doc comment to qom.rst, Paolo Bonzini, 2020/09/24
- [PULL 75/92] hw/i386/xen: Rename X86/PC specific function as xen_hvm_init_pc(), Paolo Bonzini, 2020/09/24