On Fri, Apr 05, 2013 at 02:07:52PM +0100, Richard W.M. Jones wrote:
> +/* DEBUG_SSH=1 enables the DPRINTF (debugging printf) statements in
> + * this block driver code.
> + *
> + * TRACE_LIBSSH2=<bitmask> enables tracing in libssh2 itself. Note
> + * that this requires that libssh2 was specially compiled with the
> + * `./configure --enable-debug' option, so most likely you will have
> + * to compile it yourself. The meaning of <bitmask> is described
> + * here: http://www.libssh2.org/libssh2_trace.html
> + */
> +#define DEBUG_SSH 0
> +#define TRACE_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */
> +
> +#if DEBUG_SSH
> +#define DPRINTF(fmt,...) \
> + do { \
> + fprintf(stderr, "ssh: %-15s " fmt "\n", __func__, ##__VA_ARGS__); \
> + } while (0)
> +#else
> +#define DPRINTF(fmt,...) /* nothing */
> +#endif
The following approach keeps syntax and format string error checking
even when DEBUG_SSH if 0:
#define DPRINTF(fmt, ...) \
do { \
if (DEBUG_SSH) { \
fprintf(stderr, "ssh: %-15s " fmt "\n", \
__func__, ##__VA_ARGS__); \
} \
} while (0)
It avoids DPRINTF() bitrot.
> +#define LOCK(s) do { \
> + DPRINTF("acquiring the lock"); \
> + qemu_co_mutex_lock(&s->lock); \
> + DPRINTF("acquired the lock"); \
> + } while (0)
> +
> +#define UNLOCK(s) do { \
> + qemu_co_mutex_unlock(&s->lock); \
> + DPRINTF("released the lock"); \
> + } while (0)
See ./trace-events:
qemu_co_mutex_lock_entry(void *mutex, void *self) "mutex %p self %p"
qemu_co_mutex_lock_return(void *mutex, void *self) "mutex %p self %p"
qemu_co_mutex_unlock_entry(void *mutex, void *self) "mutex %p self %p"
qemu_co_mutex_unlock_return(void *mutex, void *self) "mutex %p self %p"
This means you can get these printfs like this:
$ ./configure --enable-trace-backend=stderr
$ echo qemu_co_mutex_lock_entry >my-events
$ echo qemu_co_mutex_lock_return >>my-events
$ echo qemu_co_mutex_unlock_entry >>my-events
$ echo qemu_co_mutex_unlock_return >>my-events
$ x86_64-softmmu/qemu-system-x86_64 -trace events=my-events ...
If you want you can keep the macros but really we already have these
printfs.
