[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2 7/7] error: On abort, report where the error
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH v2 7/7] error: On abort, report where the error was created |
Date: |
Fri, 24 Jul 2015 10:14:35 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 07/23/15 16:47, Eric Blake wrote:
> On 07/23/2015 08:01 AM, Markus Armbruster wrote:
>> This is particularly useful when we abort in error_propagate(),
>> because there the stack backtrace doesn't lead to where the error was
>> created. Looks like this:
>>
>> Unexpected error in parse_block_error_action() at
>> /work/armbru/qemu/blockdev.c:322:
>> qemu-system-x86_64: -drive if=none,werror=foo: 'foo' invalid write error
>> action
>> Aborted (core dumped)
>>
>> Note: to get this example output, I monkey-patched drive_new() to pass
>> &error_abort to blockdev_init().
>>
>> To keep the error handling boiler plate from growing even more, all
>> error_setFOO() become macros expanding into error_setFOO_internal()
>> with additional __FILE__, __LINE__, __func__ arguments. Not exactly
>> pretty, but it works.
>>
>> The macro trickery breaks down when you take the address of an
>> error_setFOO(). Fortunately, we do that in just one place: qemu-ga's
>> Windows VSS provider and requester DLL wants to call
>> error_setg_win32() through a function pointer "to avoid linking glib
>> to the DLL". Use error_setg_win32_internal() there. The use of the
>> function pointer is already wrapped in a macro, so the churn isn't
>> bad.
>>
>> Code size increases by some 35KiB for me (0.7%). Tolerable. Could be
>> less if we passed relative rather than absolute source file names to
>> the compiler, or forwent reporting __func__.
>>
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>> include/qapi/error.h | 43 +++++++++++++++++++++++++++--------
>> qga/vss-win32.c | 2 +-
>> qga/vss-win32/requester.cpp | 5 +++--
>> qga/vss-win32/requester.h | 6 +++--
>> util/error.c | 55
>> ++++++++++++++++++++++++++++++++-------------
>> 5 files changed, 81 insertions(+), 30 deletions(-)
>>
>
>> +++ b/qga/vss-win32/requester.cpp
>> @@ -23,8 +23,9 @@
>> /* Call QueryStatus every 10 ms while waiting for frozen event */
>> #define VSS_TIMEOUT_EVENT_MSEC 10
>>
>> -#define err_set(e, err, fmt, ...) \
>> - ((e)->error_setg_win32((e)->errp, err, fmt, ## __VA_ARGS__))
>> +#define err_set(e, err, fmt, ...) \
>> + ((e)->error_setg_win32((e)->errp, __FILE__, __LINE__, __func__, \
>> + err, fmt, ## __VA_ARGS__))
>
> Indentation looks odd here, but not fatal.
>
>> -void error_setg_errno(Error **errp, int os_errno, const char *fmt, ...)
>> +void error_setg_errno_internal(Error **errp,
>> + const char *src, int line, const char *func,
>> + int os_errno, const char *fmt, ...)
>
> Indentation off again.
>
> Those are minor, and could be fixed by maintainer.
> Reviewed-by: Eric Blake <address@hidden>
>
I'm going to freeload in the wake of Eric's review, and just say "thank
you" for including __func__.
Acked-by: Laszlo Ersek <address@hidden>
- [Qemu-devel] [PATCH v2 0/7] error: On abort, report where the error was created, Markus Armbruster, 2015/07/23
- [Qemu-devel] [PATCH v2 2/7] error: Make error_setg() a function, Markus Armbruster, 2015/07/23
- [Qemu-devel] [PATCH v2 3/7] qga: Clean up unnecessarily dirty casts, Markus Armbruster, 2015/07/23
- [Qemu-devel] [PATCH v2 7/7] error: On abort, report where the error was created, Markus Armbruster, 2015/07/23
- [Qemu-devel] [PATCH v2 1/7] error: De-duplicate code creating Error objects, Markus Armbruster, 2015/07/23
- [Qemu-devel] [PATCH v2 6/7] error: Revamp interface documentation, Markus Armbruster, 2015/07/23
[Qemu-devel] [PATCH v2 5/7] error: error_set_errno() is unused, drop, Markus Armbruster, 2015/07/23