Commit b5204106 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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'
parents adf4bfc4 c77ae0b8

fs/proc/kmsg.c

+0 −2
Original line number Diff line number Diff line
@@ -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);

include/linux/printk.h

+0 −7
Original line number Diff line number Diff line
@@ -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;

include/linux/syslog.h

+3 −0
Original line number Diff line number Diff line
@@ -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 */

kernel/printk/printk.c

+4 −15
Original line number Diff line number Diff line
@@ -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:

lib/vsprintf.c

+28 −23
Original line number Diff line number Diff line
@@ -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);