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printk changes for 6.1

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Merge tag 'printk-for-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:

 - Initialize pointer hashing using the system workqueue. It avoids
   taking locks in printk()/vsprintf() code path

 - Misc code clean up

* tag 'printk-for-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printk: Mark __printk percpu data ready __ro_after_init
  printk: Remove bogus comment vs. boot consoles
  printk: Remove write only variable nr_ext_console_drivers
  printk: Declare log_wait properly
  printk: Make pr_flush() static
  lib/vsprintf: Initialize vsprintf's pointer hash once the random core is ready.
  lib/vsprintf: Remove static_branch_likely() from __ptr_to_hashval().
  lib/vnsprintf: add const modifier for param 'bitmap'
This commit is contained in:
Linus Torvalds 2022-10-10 11:24:19 -07:00
commit b520410654
5 changed files with 35 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/proc/kmsg.c
View File

@ -17,8 +17,6 @@
#include <asm/io.h>
extern wait_queue_head_t log_wait;
static int kmsg_open(struct inode * inode, struct file * file)
{
return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);

7
include/linux/printk.h
View File

@ -169,8 +169,6 @@ extern void __printk_safe_exit(void);
#define printk_deferred_enter __printk_safe_enter
#define printk_deferred_exit __printk_safe_exit
extern bool pr_flush(int timeout_ms, bool reset_on_progress);
/*
* Please don't use printk_ratelimit(), because it shares ratelimiting state
* with all other unrelated printk_ratelimit() callsites. Instead use
@ -221,11 +219,6 @@ static inline void printk_deferred_exit(void)
{
}
static inline bool pr_flush(int timeout_ms, bool reset_on_progress)
{
return true;
}
static inline int printk_ratelimit(void)
{
return 0;

3
include/linux/syslog.h
View File

@ -8,6 +8,8 @@
#ifndef _LINUX_SYSLOG_H
#define _LINUX_SYSLOG_H
#include <linux/wait.h>
/* Close the log. Currently a NOP. */
#define SYSLOG_ACTION_CLOSE 0
/* Open the log. Currently a NOP. */
@ -35,5 +37,6 @@
#define SYSLOG_FROM_PROC 1
int do_syslog(int type, char __user *buf, int count, int source);
extern wait_queue_head_t log_wait;
#endif /* _LINUX_SYSLOG_H */

19
kernel/printk/printk.c
View File

@ -220,9 +220,6 @@ int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
}
#endif /* CONFIG_PRINTK && CONFIG_SYSCTL */
/* Number of registered extended console drivers. */
static int nr_ext_console_drivers;
/*
* Helper macros to handle lockdep when locking/unlocking console_sem. We use
* macros instead of functions so that _RET_IP_ contains useful information.
@ -433,7 +430,7 @@ static struct printk_ringbuffer *prb = &printk_rb_static;
* per_cpu_areas are initialised. This variable is set to true when
* it's safe to access per-CPU data.
*/
static bool __printk_percpu_data_ready __read_mostly;
static bool __printk_percpu_data_ready __ro_after_init;
bool printk_percpu_data_ready(void)
{
@ -2296,6 +2293,7 @@ asmlinkage __visible int _printk(const char *fmt, ...)
}
EXPORT_SYMBOL(_printk);
static bool pr_flush(int timeout_ms, bool reset_on_progress);
static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress);
#else /* CONFIG_PRINTK */
@ -2330,6 +2328,7 @@ static void call_console_driver(struct console *con, const char *text, size_t le
{
}
static bool suppress_message_printing(int level) { return false; }
static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; }
static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; }
#endif /* CONFIG_PRINTK */
@ -3186,9 +3185,6 @@ void register_console(struct console *newcon)
console_drivers->next = newcon;
}
if (newcon->flags & CON_EXTENDED)
nr_ext_console_drivers++;
newcon->dropped = 0;
if (newcon->flags & CON_PRINTBUFFER) {
/* Get a consistent copy of @syslog_seq. */
@ -3213,9 +3209,6 @@ void register_console(struct console *newcon)
if (bootcon_enabled &&
((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
!keep_bootcon) {
/* We need to iterate through all boot consoles, to make
* sure we print everything out, before we unregister them.
*/
for_each_console(con)
if (con->flags & CON_BOOT)
unregister_console(con);
@ -3254,9 +3247,6 @@ int unregister_console(struct console *console)
if (res)
goto out_disable_unlock;
if (console->flags & CON_EXTENDED)
nr_ext_console_drivers--;
/*
* If this isn't the last console and it has CON_CONSDEV set, we
* need to set it on the next preferred console.
@ -3438,11 +3428,10 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
* Context: Process context. May sleep while acquiring console lock.
* Return: true if all enabled printers are caught up.
*/
bool pr_flush(int timeout_ms, bool reset_on_progress)
static bool pr_flush(int timeout_ms, bool reset_on_progress)
{
return __pr_flush(NULL, timeout_ms, reset_on_progress);
}
EXPORT_SYMBOL(pr_flush);
/*
* Delayed printk version, for scheduler-internal messages:

51
lib/vsprintf.c
View File

@ -750,37 +750,42 @@ static int __init debug_boot_weak_hash_enable(char *str)
}
early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable);
static DEFINE_STATIC_KEY_FALSE(filled_random_ptr_key);
static bool filled_random_ptr_key __read_mostly;
static siphash_key_t ptr_key __read_mostly;
static void fill_ptr_key_workfn(struct work_struct *work);
static DECLARE_DELAYED_WORK(fill_ptr_key_work, fill_ptr_key_workfn);
static void enable_ptr_key_workfn(struct work_struct *work)
static void fill_ptr_key_workfn(struct work_struct *work)
{
static_branch_enable(&filled_random_ptr_key);
if (!rng_is_initialized()) {
queue_delayed_work(system_unbound_wq, &fill_ptr_key_work, HZ * 2);
return;
}
get_random_bytes(&ptr_key, sizeof(ptr_key));
/* Pairs with smp_rmb() before reading ptr_key. */
smp_wmb();
WRITE_ONCE(filled_random_ptr_key, true);
}
static int __init vsprintf_init_hashval(void)
{
fill_ptr_key_workfn(NULL);
return 0;
}
subsys_initcall(vsprintf_init_hashval)
/* Maps a pointer to a 32 bit unique identifier. */
static inline int __ptr_to_hashval(const void *ptr, unsigned long *hashval_out)
{
static siphash_key_t ptr_key __read_mostly;
unsigned long hashval;
if (!static_branch_likely(&filled_random_ptr_key)) {
static bool filled = false;
static DEFINE_SPINLOCK(filling);
static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn);
unsigned long flags;
if (!system_unbound_wq || !rng_is_initialized() ||
!spin_trylock_irqsave(&filling, flags))
return -EAGAIN;
if (!filled) {
get_random_bytes(&ptr_key, sizeof(ptr_key));
queue_work(system_unbound_wq, &enable_ptr_key_work);
filled = true;
}
spin_unlock_irqrestore(&filling, flags);
}
if (!READ_ONCE(filled_random_ptr_key))
return -EBUSY;
/* Pairs with smp_wmb() after writing ptr_key. */
smp_rmb();
#ifdef CONFIG_64BIT
hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);
@ -1189,7 +1194,7 @@ char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
}
static noinline_for_stack
char *bitmap_string(char *buf, char *end, unsigned long *bitmap,
char *bitmap_string(char *buf, char *end, const unsigned long *bitmap,
struct printf_spec spec, const char *fmt)
{
const int CHUNKSZ = 32;
@ -1233,7 +1238,7 @@ char *bitmap_string(char *buf, char *end, unsigned long *bitmap,
}
static noinline_for_stack
char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap,
char *bitmap_list_string(char *buf, char *end, const unsigned long *bitmap,
struct printf_spec spec, const char *fmt)
{
int nr_bits = max_t(int, spec.field_width, 0);