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commit c4703acd6d4a58dc4b31ad2a8f8b14becb898d25
parent a448c643bc49f14bb3aae68ee7085b4c7f6207d8
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sat,  9 Mar 2019 09:22:42 -0800

Merge tag 'printk-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk

Pull printk updates from Petr Mladek:

 - Allow to sort mixed lines by an extra information about the caller

 - Remove no longer used LOG_PREFIX.

 - Some clean up and documentation update.

* tag 'printk-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  printk/docs: Add extra integer types to printk-formats
  printk: Remove no longer used LOG_PREFIX.
  lib/vsprintf: Remove %pCr remnant in comment
  printk: Pass caller information to log_store().
  printk: Add caller information to printk() output.

Diffstat:
MDocumentation/core-api/printk-formats.rst | 8++++++++
Minclude/linux/kern_levels.h | 2+-
Minclude/linux/printk.h | 1-
Mkernel/printk/printk.c | 90+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------------------
Mlib/Kconfig.debug | 17+++++++++++++++++
Mlib/vsprintf.c | 1-
6 files changed, 96 insertions(+), 23 deletions(-)

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst @@ -13,6 +13,10 @@ Integer types If variable is of Type, use printk format specifier: ------------------------------------------------------------ + char %hhd or %hhx + unsigned char %hhu or %hhx + short int %hd or %hx + unsigned short int %hu or %hx int %d or %x unsigned int %u or %x long %ld or %lx @@ -21,6 +25,10 @@ Integer types unsigned long long %llu or %llx size_t %zu or %zx ssize_t %zd or %zx + s8 %hhd or %hhx + u8 %hhu or %hhx + s16 %hd or %hx + u16 %hu or %hx s32 %d or %x u32 %u or %x s64 %lld or %llx diff --git a/include/linux/kern_levels.h b/include/linux/kern_levels.h @@ -14,7 +14,7 @@ #define KERN_INFO KERN_SOH "6" /* informational */ #define KERN_DEBUG KERN_SOH "7" /* debug-level messages */ -#define KERN_DEFAULT KERN_SOH "d" /* the default kernel loglevel */ +#define KERN_DEFAULT "" /* the default kernel loglevel */ /* * Annotation for a "continued" line of log printout (only done after a diff --git a/include/linux/printk.h b/include/linux/printk.h @@ -18,7 +18,6 @@ static inline int printk_get_level(const char *buffer) if (buffer[0] == KERN_SOH_ASCII && buffer[1]) { switch (buffer[1]) { case '0' ... '7': - case 'd': /* KERN_DEFAULT */ case 'c': /* KERN_CONT */ return buffer[1]; } diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c @@ -344,7 +344,6 @@ static int console_msg_format = MSG_FORMAT_DEFAULT; enum log_flags { LOG_NEWLINE = 2, /* text ended with a newline */ - LOG_PREFIX = 4, /* text started with a prefix */ LOG_CONT = 8, /* text is a fragment of a continuation line */ }; @@ -356,6 +355,9 @@ struct printk_log { u8 facility; /* syslog facility */ u8 flags:5; /* internal record flags */ u8 level:3; /* syslog level */ +#ifdef CONFIG_PRINTK_CALLER + u32 caller_id; /* thread id or processor id */ +#endif } #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS __packed __aligned(4) @@ -422,7 +424,11 @@ static u64 exclusive_console_stop_seq; static u64 clear_seq; static u32 clear_idx; +#ifdef CONFIG_PRINTK_CALLER +#define PREFIX_MAX 48 +#else #define PREFIX_MAX 32 +#endif #define LOG_LINE_MAX (1024 - PREFIX_MAX) #define LOG_LEVEL(v) ((v) & 0x07) @@ -577,7 +583,7 @@ static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, } /* insert record into the buffer, discard old ones, update heads */ -static int log_store(int facility, int level, +static int log_store(u32 caller_id, int facility, int level, enum log_flags flags, u64 ts_nsec, const char *dict, u16 dict_len, const char *text, u16 text_len) @@ -625,6 +631,9 @@ static int log_store(int facility, int level, msg->ts_nsec = ts_nsec; else msg->ts_nsec = local_clock(); +#ifdef CONFIG_PRINTK_CALLER + msg->caller_id = caller_id; +#endif memset(log_dict(msg) + dict_len, 0, pad_len); msg->len = size; @@ -688,12 +697,21 @@ static ssize_t msg_print_ext_header(char *buf, size_t size, struct printk_log *msg, u64 seq) { u64 ts_usec = msg->ts_nsec; + char caller[20]; +#ifdef CONFIG_PRINTK_CALLER + u32 id = msg->caller_id; + + snprintf(caller, sizeof(caller), ",caller=%c%u", + id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); +#else + caller[0] = '\0'; +#endif do_div(ts_usec, 1000); - return scnprintf(buf, size, "%u,%llu,%llu,%c;", - (msg->facility << 3) | msg->level, seq, ts_usec, - msg->flags & LOG_CONT ? 'c' : '-'); + return scnprintf(buf, size, "%u,%llu,%llu,%c%s;", + (msg->facility << 3) | msg->level, seq, ts_usec, + msg->flags & LOG_CONT ? 'c' : '-', caller); } static ssize_t msg_print_ext_body(char *buf, size_t size, @@ -1038,6 +1056,9 @@ void log_buf_vmcoreinfo_setup(void) VMCOREINFO_OFFSET(printk_log, len); VMCOREINFO_OFFSET(printk_log, text_len); VMCOREINFO_OFFSET(printk_log, dict_len); +#ifdef CONFIG_PRINTK_CALLER + VMCOREINFO_OFFSET(printk_log, caller_id); +#endif } #endif @@ -1236,10 +1257,23 @@ static size_t print_time(u64 ts, char *buf) { unsigned long rem_nsec = do_div(ts, 1000000000); - return sprintf(buf, "[%5lu.%06lu] ", + return sprintf(buf, "[%5lu.%06lu]", (unsigned long)ts, rem_nsec / 1000); } +#ifdef CONFIG_PRINTK_CALLER +static size_t print_caller(u32 id, char *buf) +{ + char caller[12]; + + snprintf(caller, sizeof(caller), "%c%u", + id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); + return sprintf(buf, "[%6s]", caller); +} +#else +#define print_caller(id, buf) 0 +#endif + static size_t print_prefix(const struct printk_log *msg, bool syslog, bool time, char *buf) { @@ -1247,8 +1281,17 @@ static size_t print_prefix(const struct printk_log *msg, bool syslog, if (syslog) len = print_syslog((msg->facility << 3) | msg->level, buf); + if (time) len += print_time(msg->ts_nsec, buf + len); + + len += print_caller(msg->caller_id, buf + len); + + if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { + buf[len++] = ' '; + buf[len] = '\0'; + } + return len; } @@ -1752,6 +1795,12 @@ static inline void printk_delay(void) } } +static inline u32 printk_caller_id(void) +{ + return in_task() ? task_pid_nr(current) : + 0x80000000 + raw_smp_processor_id(); +} + /* * Continuation lines are buffered, and not committed to the record buffer * until the line is complete, or a race forces it. The line fragments @@ -1761,7 +1810,7 @@ static inline void printk_delay(void) static struct cont { char buf[LOG_LINE_MAX]; size_t len; /* length == 0 means unused buffer */ - struct task_struct *owner; /* task of first print*/ + u32 caller_id; /* printk_caller_id() of first print */ u64 ts_nsec; /* time of first print */ u8 level; /* log level of first message */ u8 facility; /* log facility of first message */ @@ -1773,12 +1822,13 @@ static void cont_flush(void) if (cont.len == 0) return; - log_store(cont.facility, cont.level, cont.flags, cont.ts_nsec, - NULL, 0, cont.buf, cont.len); + log_store(cont.caller_id, cont.facility, cont.level, cont.flags, + cont.ts_nsec, NULL, 0, cont.buf, cont.len); cont.len = 0; } -static bool cont_add(int facility, int level, enum log_flags flags, const char *text, size_t len) +static bool cont_add(u32 caller_id, int facility, int level, + enum log_flags flags, const char *text, size_t len) { /* If the line gets too long, split it up in separate records. */ if (cont.len + len > sizeof(cont.buf)) { @@ -1789,7 +1839,7 @@ static bool cont_add(int facility, int level, enum log_flags flags, const char * if (!cont.len) { cont.facility = facility; cont.level = level; - cont.owner = current; + cont.caller_id = caller_id; cont.ts_nsec = local_clock(); cont.flags = flags; } @@ -1809,13 +1859,15 @@ static bool cont_add(int facility, int level, enum log_flags flags, const char * static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len) { + const u32 caller_id = printk_caller_id(); + /* * If an earlier line was buffered, and we're a continuation - * write from the same process, try to add it to the buffer. + * write from the same context, try to add it to the buffer. */ if (cont.len) { - if (cont.owner == current && (lflags & LOG_CONT)) { - if (cont_add(facility, level, lflags, text, text_len)) + if (cont.caller_id == caller_id && (lflags & LOG_CONT)) { + if (cont_add(caller_id, facility, level, lflags, text, text_len)) return text_len; } /* Otherwise, make sure it's flushed */ @@ -1828,12 +1880,13 @@ static size_t log_output(int facility, int level, enum log_flags lflags, const c /* If it doesn't end in a newline, try to buffer the current line */ if (!(lflags & LOG_NEWLINE)) { - if (cont_add(facility, level, lflags, text, text_len)) + if (cont_add(caller_id, facility, level, lflags, text, text_len)) return text_len; } /* Store it in the record log */ - return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len); + return log_store(caller_id, facility, level, lflags, 0, + dict, dictlen, text, text_len); } /* Must be called under logbuf_lock. */ @@ -1867,9 +1920,6 @@ int vprintk_store(int facility, int level, case '0' ... '7': if (level == LOGLEVEL_DEFAULT) level = kern_level - '0'; - /* fallthrough */ - case 'd': /* KERN_DEFAULT */ - lflags |= LOG_PREFIX; break; case 'c': /* KERN_CONT */ lflags |= LOG_CONT; @@ -1884,7 +1934,7 @@ int vprintk_store(int facility, int level, level = default_message_loglevel; if (dict) - lflags |= LOG_PREFIX|LOG_NEWLINE; + lflags |= LOG_NEWLINE; return log_output(facility, level, lflags, dict, dictlen, text, text_len); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug @@ -17,6 +17,23 @@ config PRINTK_TIME The behavior is also controlled by the kernel command line parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst +config PRINTK_CALLER + bool "Show caller information on printks" + depends on PRINTK + help + Selecting this option causes printk() to add a caller "thread id" (if + in task context) or a caller "processor id" (if not in task context) + to every message. + + This option is intended for environments where multiple threads + concurrently call printk() for many times, for it is difficult to + interpret without knowing where these lines (or sometimes individual + line which was divided into multiple lines due to race) came from. + + Since toggling after boot makes the code racy, currently there is + no option to enable/disable at the kernel command line parameter or + sysfs interface. + config CONSOLE_LOGLEVEL_DEFAULT int "Default console loglevel (1-15)" range 1 15 diff --git a/lib/vsprintf.c b/lib/vsprintf.c @@ -1931,7 +1931,6 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, * (legacy clock framework) of the clock * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address * (legacy clock framework) of the clock - * - 'Cr' For a clock, it prints the current rate of the clock * - 'G' For flags to be printed as a collection of symbolic strings that would * construct the specific value. Supported flags given by option: * p page flags (see struct page) given as pointer to unsigned long