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printk changes for 6.13

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Merge tag 'printk-for-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:

 - Print more precise information about the printk log buffer memory
   usage.

 - Make sure that the sysrq title is shown on the console even when
   deferred.

 - Do not enable earlycon by `console=` which is meant to disable the
   default console.

* tag 'printk-for-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printk: add dummy printk_force_console_enter/exit helpers
  tty: sysrq: Use printk_force_console context on __handle_sysrq
  printk: Introduce FORCE_CON flag
  printk: Improve memory usage logging during boot
  init: Don't proxy `console=` to earlycon
This commit is contained in:
Linus Torvalds 2024-11-20 09:21:11 -08:00
commit 7d66d3ab13
7 changed files with 102 additions and 23 deletions
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23
drivers/tty/serial/earlycon.c
View File

@ -248,6 +248,29 @@ static int __init param_setup_earlycon(char *buf)
}
early_param("earlycon", param_setup_earlycon);
/*
* The `console` parameter is overloaded. It's handled here as an early param
* and in `printk.c` as a late param. It's possible to specify an early
* `bootconsole` using `earlycon=uartXXXX` (handled above), or via
* the `console=uartXXX` alias. See the comment in `8250_early.c`.
*/
static int __init param_setup_earlycon_console_alias(char *buf)
{
/*
* A plain `console` parameter must not enable the SPCR `bootconsole`
* like a plain `earlycon` does.
*
* A `console=` parameter that specifies an empty value is used to
* disable the `console`, not the `earlycon` `bootconsole`. The
* disabling of the `console` is handled by `printk.c`.
*/
if (!buf || !buf[0])
return 0;
return param_setup_earlycon(buf);
}
early_param("console", param_setup_earlycon_console_alias);
#ifdef CONFIG_OF_EARLY_FLATTREE
int __init of_setup_earlycon(const struct earlycon_id *match,

18
drivers/tty/sysrq.c
View File

@ -583,7 +583,6 @@ static void __sysrq_put_key_op(u8 key, const struct sysrq_key_op *op_p)
void __handle_sysrq(u8 key, bool check_mask)
{
const struct sysrq_key_op *op_p;
int orig_log_level;
int orig_suppress_printk;
int i;
@ -593,13 +592,12 @@ void __handle_sysrq(u8 key, bool check_mask)
rcu_sysrq_start();
rcu_read_lock();
/*
* Raise the apparent loglevel to maximum so that the sysrq header
* is shown to provide the user with positive feedback. We do not
* simply emit this at KERN_EMERG as that would change message
* routing in the consumers of /proc/kmsg.
* Enter in the force_console context so that sysrq header is shown to
* provide the user with positive feedback. We do not simply emit this
* at KERN_EMERG as that would change message routing in the consumers
* of /proc/kmsg.
*/
orig_log_level = console_loglevel;
console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
printk_force_console_enter();
op_p = __sysrq_get_key_op(key);
if (op_p) {
@ -609,11 +607,11 @@ void __handle_sysrq(u8 key, bool check_mask)
*/
if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
pr_info("%s\n", op_p->action_msg);
console_loglevel = orig_log_level;
printk_force_console_exit();
op_p->handler(key);
} else {
pr_info("This sysrq operation is disabled.\n");
console_loglevel = orig_log_level;
printk_force_console_exit();
}
} else {
pr_info("HELP : ");
@ -631,7 +629,7 @@ void __handle_sysrq(u8 key, bool check_mask)
}
}
pr_cont("\n");
console_loglevel = orig_log_level;
printk_force_console_exit();
}
rcu_read_unlock();
rcu_sysrq_end();

11
include/linux/printk.h
View File

@ -166,6 +166,9 @@ __printf(1, 2) __cold int _printk_deferred(const char *fmt, ...);
extern void __printk_deferred_enter(void);
extern void __printk_deferred_exit(void);
extern void printk_force_console_enter(void);
extern void printk_force_console_exit(void);
/*
* The printk_deferred_enter/exit macros are available only as a hack for
* some code paths that need to defer all printk console printing. Interrupts
@ -229,6 +232,14 @@ static inline void printk_deferred_exit(void)
{
}
static inline void printk_force_console_enter(void)
{
}
static inline void printk_force_console_exit(void)
{
}
static inline int printk_ratelimit(void)
{
return 0;

5
init/main.c
View File

@ -754,10 +754,7 @@ static int __init do_early_param(char *param, char *val,
const struct obs_kernel_param *p;
for (p = __setup_start; p < __setup_end; p++) {
if ((p->early && parameq(param, p->str)) ||
(strcmp(param, "console") == 0 &&
strcmp(p->str, "earlycon") == 0)
) {
if (p->early && parameq(param, p->str)) {
if (p->setup_func(val) != 0)
pr_warn("Malformed early option '%s'\n", param);
}

3
kernel/printk/internal.h
View File

@ -53,6 +53,8 @@ int devkmsg_sysctl_set_loglvl(const struct ctl_table *table, int write,
/* Flags for a single printk record. */
enum printk_info_flags {
/* always show on console, ignore console_loglevel */
LOG_FORCE_CON = 1,
LOG_NEWLINE = 2, /* text ended with a newline */
LOG_CONT = 8, /* text is a fragment of a continuation line */
};
@ -90,6 +92,7 @@ bool printk_percpu_data_ready(void);
void defer_console_output(void);
bool is_printk_legacy_deferred(void);
bool is_printk_force_console(void);
u16 printk_parse_prefix(const char *text, int *level,
enum printk_info_flags *flags);

47
kernel/printk/printk.c
View File

@ -1157,6 +1157,17 @@ static unsigned int __init add_to_rb(struct printk_ringbuffer *rb,
static char setup_text_buf[PRINTKRB_RECORD_MAX] __initdata;
static void print_log_buf_usage_stats(void)
{
unsigned int descs_count = log_buf_len >> PRB_AVGBITS;
size_t meta_data_size;
meta_data_size = descs_count * (sizeof(struct prb_desc) + sizeof(struct printk_info));
pr_info("log buffer data + meta data: %u + %zu = %zu bytes\n",
log_buf_len, meta_data_size, log_buf_len + meta_data_size);
}
void __init setup_log_buf(int early)
{
struct printk_info *new_infos;
@ -1186,20 +1197,25 @@ void __init setup_log_buf(int early)
if (!early && !new_log_buf_len)
log_buf_add_cpu();
if (!new_log_buf_len)
if (!new_log_buf_len) {
/* Show the memory stats only once. */
if (!early)
goto out;
return;
}
new_descs_count = new_log_buf_len >> PRB_AVGBITS;
if (new_descs_count == 0) {
pr_err("new_log_buf_len: %lu too small\n", new_log_buf_len);
return;
goto out;
}
new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN);
if (unlikely(!new_log_buf)) {
pr_err("log_buf_len: %lu text bytes not available\n",
new_log_buf_len);
return;
goto out;
}
new_descs_size = new_descs_count * sizeof(struct prb_desc);
@ -1262,7 +1278,7 @@ void __init setup_log_buf(int early)
prb_next_seq(&printk_rb_static) - seq);
}
pr_info("log_buf_len: %u bytes\n", log_buf_len);
print_log_buf_usage_stats();
pr_info("early log buf free: %u(%u%%)\n",
free, (free * 100) / __LOG_BUF_LEN);
return;
@ -1271,6 +1287,8 @@ err_free_descs:
memblock_free(new_descs, new_descs_size);
err_free_log_buf:
memblock_free(new_log_buf, new_log_buf_len);
out:
print_log_buf_usage_stats();
}
static bool __read_mostly ignore_loglevel;
@ -1320,11 +1338,11 @@ static void boot_delay_msec(int level)
{
unsigned long long k;
unsigned long timeout;
bool suppress = !is_printk_force_console() &&
suppress_message_printing(level);
if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING)
|| suppress_message_printing(level)) {
if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) || suppress)
return;
}
k = (unsigned long long)loops_per_msec * boot_delay;
@ -2274,6 +2292,9 @@ int vprintk_store(int facility, int level,
if (dev_info)
flags |= LOG_NEWLINE;
if (is_printk_force_console())
flags |= LOG_FORCE_CON;
if (flags & LOG_CONT) {
prb_rec_init_wr(&r, reserve_size);
if (prb_reserve_in_last(&e, prb, &r, caller_id, PRINTKRB_RECORD_MAX)) {
@ -2281,6 +2302,9 @@ int vprintk_store(int facility, int level,
facility, &flags, fmt, args);
r.info->text_len += text_len;
if (flags & LOG_FORCE_CON)
r.info->flags |= LOG_FORCE_CON;
if (flags & LOG_NEWLINE) {
r.info->flags |= LOG_NEWLINE;
prb_final_commit(&e);
@ -2948,6 +2972,7 @@ bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
struct printk_info info;
struct printk_record r;
size_t len = 0;
bool force_con;
/*
* Formatting extended messages requires a separate buffer, so use the
@ -2966,9 +2991,13 @@ bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
pmsg->seq = r.info->seq;
pmsg->dropped = r.info->seq - seq;
force_con = r.info->flags & LOG_FORCE_CON;
/* Skip record that has level above the console loglevel. */
if (may_suppress && suppress_message_printing(r.info->level))
/*
* Skip records that are not forced to be printed on consoles and that
* has level above the console loglevel.
*/
if (!force_con && may_suppress && suppress_message_printing(r.info->level))
goto out;
if (is_extended) {

18
kernel/printk/printk_safe.c
View File

@ -12,6 +12,24 @@
#include "internal.h"
/* Context where printk messages are never suppressed */
static atomic_t force_con;
void printk_force_console_enter(void)
{
atomic_inc(&force_con);
}
void printk_force_console_exit(void)
{
atomic_dec(&force_con);
}
bool is_printk_force_console(void)
{
return atomic_read(&force_con);
}
static DEFINE_PER_CPU(int, printk_context);
/* Can be preempted by NMI. */