diff options
| -rw-r--r-- | include/qemu/log.h | 1 | ||||
| -rw-r--r-- | util/log.c | 163 |
2 files changed, 128 insertions, 36 deletions
diff --git a/include/qemu/log.h b/include/qemu/log.h index a325bca661..c5643d8dd5 100644 --- a/include/qemu/log.h +++ b/include/qemu/log.h @@ -34,6 +34,7 @@ bool qemu_log_separate(void); #define CPU_LOG_PLUGIN (1 << 18) /* LOG_STRACE is used for user-mode strace logging. */ #define LOG_STRACE (1 << 19) +#define LOG_PER_THREAD (1 << 20) /* Lock/unlock output. */ diff --git a/util/log.c b/util/log.c index df0710720f..d6eb0378c3 100644 --- a/util/log.c +++ b/util/log.c @@ -27,6 +27,9 @@ #include "qemu/thread.h" #include "qemu/lockable.h" #include "qemu/rcu.h" +#ifdef CONFIG_LINUX +#include <sys/syscall.h> +#endif typedef struct RCUCloseFILE { @@ -38,22 +41,40 @@ typedef struct RCUCloseFILE { static QemuMutex global_mutex; static char *global_filename; static FILE *global_file; +static __thread FILE *thread_file; int qemu_loglevel; -static int log_append = 0; +static bool log_append; +static bool log_per_thread; static GArray *debug_regions; /* Returns true if qemu_log() will really write somewhere. */ bool qemu_log_enabled(void) { - return qatomic_read(&global_file) != NULL; + return log_per_thread || qatomic_read(&global_file) != NULL; } /* Returns true if qemu_log() will write somewhere other than stderr. */ bool qemu_log_separate(void) { - FILE *logfile = qatomic_read(&global_file); - return logfile && logfile != stderr; + if (log_per_thread) { + return true; + } else { + FILE *logfile = qatomic_read(&global_file); + return logfile && logfile != stderr; + } +} + +static int log_thread_id(void) +{ +#ifdef CONFIG_GETTID + return gettid(); +#elif defined(SYS_gettid) + return syscall(SYS_gettid); +#else + static int counter; + return qatomic_fetch_inc(&counter); +#endif } /* Lock/unlock output. */ @@ -62,20 +83,34 @@ FILE *qemu_log_trylock(void) { FILE *logfile; - rcu_read_lock(); - /* - * FIXME: typeof_strip_qual, as used by qatomic_rcu_read, - * does not work with pointers to undefined structures, - * such as we have with struct _IO_FILE and musl libc. - * Since all we want is a read of a pointer, cast to void**, - * which does work with typeof_strip_qual. - */ - logfile = qatomic_rcu_read((void **)&global_file); - if (logfile) { - qemu_flockfile(logfile); - } else { - rcu_read_unlock(); + logfile = thread_file; + if (!logfile) { + if (log_per_thread) { + g_autofree char *filename + = g_strdup_printf(global_filename, log_thread_id()); + logfile = fopen(filename, "w"); + if (!logfile) { + return NULL; + } + thread_file = logfile; + } else { + rcu_read_lock(); + /* + * FIXME: typeof_strip_qual, as used by qatomic_rcu_read, + * does not work with pointers to undefined structures, + * such as we have with struct _IO_FILE and musl libc. + * Since all we want is a read of a pointer, cast to void**, + * which does work with typeof_strip_qual. + */ + logfile = qatomic_rcu_read((void **)&global_file); + if (!logfile) { + rcu_read_unlock(); + return NULL; + } + } } + + qemu_flockfile(logfile); return logfile; } @@ -84,7 +119,9 @@ void qemu_log_unlock(FILE *logfile) if (logfile) { fflush(logfile); qemu_funlockfile(logfile); - rcu_read_unlock(); + if (!log_per_thread) { + rcu_read_unlock(); + } } } @@ -112,40 +149,81 @@ static void rcu_close_file(RCUCloseFILE *r) g_free(r); } +/** + * valid_filename_template: + * + * Validate the filename template. Require %d if per_thread, allow it + * otherwise; require no other % within the template. + */ + +typedef enum { + vft_error, + vft_stderr, + vft_strdup, + vft_pid_printf, +} ValidFilenameTemplateResult; + +static ValidFilenameTemplateResult +valid_filename_template(const char *filename, bool per_thread, Error **errp) +{ + if (filename) { + char *pidstr = strstr(filename, "%"); + + if (pidstr) { + /* We only accept one %d, no other format strings */ + if (pidstr[1] != 'd' || strchr(pidstr + 2, '%')) { + error_setg(errp, "Bad logfile template: %s", filename); + return 0; + } + return per_thread ? vft_strdup : vft_pid_printf; + } + } + if (per_thread) { + error_setg(errp, "Filename template with '%%d' required for 'tid'"); + return vft_error; + } + return filename ? vft_strdup : vft_stderr; +} + /* enable or disable low levels log */ static bool qemu_set_log_internal(const char *filename, bool changed_name, int log_flags, Error **errp) { bool need_to_open_file; bool daemonized; + bool per_thread; FILE *logfile; QEMU_LOCK_GUARD(&global_mutex); logfile = global_file; + per_thread = log_flags & LOG_PER_THREAD; + if (changed_name) { char *newname = NULL; /* - * Allow the user to include %d in their logfile which will be - * substituted with the current PID. This is useful for debugging many - * nested linux-user tasks but will result in lots of logs. - * - * filename may be NULL. In that case, log output is sent to stderr + * Once threads start opening their own log files, we have no + * easy mechanism to tell them all to close and re-open. + * There seems little cause to do so either -- this option + * will most often be used at user-only startup. */ - if (filename) { - char *pidstr = strstr(filename, "%"); + if (log_per_thread) { + error_setg(errp, "Cannot change log filename after setting 'tid'"); + return false; + } - if (pidstr) { - /* We only accept one %d, no other format strings */ - if (pidstr[1] != 'd' || strchr(pidstr + 2, '%')) { - error_setg(errp, "Bad logfile format: %s", filename); - return false; - } - newname = g_strdup_printf(filename, getpid()); - } else { - newname = g_strdup(filename); - } + switch (valid_filename_template(filename, per_thread, errp)) { + case vft_error: + return false; + case vft_stderr: + break; + case vft_strdup: + newname = g_strdup(filename); + break; + case vft_pid_printf: + newname = g_strdup_printf(filename, getpid()); + break; } g_free(global_filename); @@ -153,8 +231,18 @@ static bool qemu_set_log_internal(const char *filename, bool changed_name, filename = newname; } else { filename = global_filename; + if (per_thread && + valid_filename_template(filename, true, errp) == vft_error) { + return false; + } } + /* Once the per-thread flag is set, it cannot be unset. */ + if (per_thread) { + log_per_thread = true; + } + /* The flag itself is not relevant for need_to_open_file. */ + log_flags &= ~LOG_PER_THREAD; #ifdef CONFIG_TRACE_LOG log_flags |= LOG_TRACE; #endif @@ -163,12 +251,13 @@ static bool qemu_set_log_internal(const char *filename, bool changed_name, /* * In all cases we only log if qemu_loglevel is set. * Also: + * If per-thread, open the file for each thread in qemu_log_lock. * If not daemonized we will always log either to stderr * or to a file (if there is a filename). * If we are daemonized, we will only log if there is a filename. */ daemonized = is_daemonized(); - need_to_open_file = log_flags && (!daemonized || filename); + need_to_open_file = log_flags && !per_thread && (!daemonized || filename); if (logfile && (!need_to_open_file || changed_name)) { qatomic_rcu_set(&global_file, NULL); @@ -354,6 +443,8 @@ const QEMULogItem qemu_log_items[] = { #endif { LOG_STRACE, "strace", "log every user-mode syscall, its input, and its result" }, + { LOG_PER_THREAD, "tid", + "open a separate log file per thread; filename must contain '%d'" }, { 0, NULL, NULL }, }; |