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The various internal size limit macros have names and/or values that do not fit well to their current usage. Rename the macros so that their purpose is clear and, if needed, provide a more appropriate value. In general, the new macros and values will lead to less memory usage. The new macros are... PRINTK_MESSAGE_MAX: This is the maximum size for a formatted message on a console, devkmsg, or syslog. It does not matter which format the message has (normal or extended). It replaces the use of CONSOLE_EXT_LOG_MAX for console and devkmsg. It replaces the use of CONSOLE_LOG_MAX for syslog. Historically, normal messages have been allowed to print up to 1kB, whereas extended messages have been allowed to print up to 8kB. However, the difference in lengths of these message types is not significant and in multi-line records, normal messages are probably larger. Also, because 1kB is only slightly above the allowed record size, multi-line normal messages could be easily truncated during formatting. This new macro should be significantly larger than the allowed record size to allow sufficient space for extended or multi-line prefix text. A value of 2kB should be plenty of space. For normal messages this represents a doubling of the historically allowed amount. For extended messages it reduces the excessive 8kB size, thus reducing memory usage needed for message formatting. PRINTK_PREFIX_MAX: This is the maximum size allowed for a record prefix (used by console and syslog). It replaces PREFIX_MAX. The value is left unchanged. PRINTKRB_RECORD_MAX: This is the maximum size allowed to be reserved for a record in the ringbuffer. It is used by all readers and writers with the printk ringbuffer. It replaces LOG_LINE_MAX. Previously this was set to "1kB - PREFIX_MAX", which makes some sense if 1kB is the limit for normal message output and prefixes are enabled. However, with the allowance of larger output and the existence of multi-line records, the value is rather bizarre. Round the value up to 1kB. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230109100800.1085541-9-john.ogness@linutronix.de
106 lines
3.0 KiB
C
106 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* internal.h - printk internal definitions
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*/
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#include <linux/percpu.h>
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#if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL)
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void __init printk_sysctl_init(void);
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int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos);
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#else
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#define printk_sysctl_init() do { } while (0)
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#endif
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#ifdef CONFIG_PRINTK
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#ifdef CONFIG_PRINTK_CALLER
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#define PRINTK_PREFIX_MAX 48
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#else
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#define PRINTK_PREFIX_MAX 32
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#endif
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/*
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* the maximum size of a formatted record (i.e. with prefix added
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* per line and dropped messages or in extended message format)
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*/
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#define PRINTK_MESSAGE_MAX 2048
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/* the maximum size allowed to be reserved for a record */
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#define PRINTKRB_RECORD_MAX 1024
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/* Flags for a single printk record. */
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enum printk_info_flags {
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LOG_NEWLINE = 2, /* text ended with a newline */
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LOG_CONT = 8, /* text is a fragment of a continuation line */
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};
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__printf(4, 0)
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int vprintk_store(int facility, int level,
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const struct dev_printk_info *dev_info,
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const char *fmt, va_list args);
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__printf(1, 0) int vprintk_default(const char *fmt, va_list args);
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__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
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bool printk_percpu_data_ready(void);
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#define printk_safe_enter_irqsave(flags) \
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do { \
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local_irq_save(flags); \
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__printk_safe_enter(); \
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} while (0)
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#define printk_safe_exit_irqrestore(flags) \
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do { \
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__printk_safe_exit(); \
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local_irq_restore(flags); \
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} while (0)
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void defer_console_output(void);
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u16 printk_parse_prefix(const char *text, int *level,
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enum printk_info_flags *flags);
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#else
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#define PRINTK_PREFIX_MAX 0
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#define PRINTK_MESSAGE_MAX 0
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#define PRINTKRB_RECORD_MAX 0
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/*
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* In !PRINTK builds we still export console_sem
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* semaphore and some of console functions (console_unlock()/etc.), so
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* printk-safe must preserve the existing local IRQ guarantees.
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*/
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#define printk_safe_enter_irqsave(flags) local_irq_save(flags)
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#define printk_safe_exit_irqrestore(flags) local_irq_restore(flags)
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static inline bool printk_percpu_data_ready(void) { return false; }
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#endif /* CONFIG_PRINTK */
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/**
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* struct printk_buffers - Buffers to read/format/output printk messages.
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* @outbuf: After formatting, contains text to output.
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* @scratchbuf: Used as temporary ringbuffer reading and string-print space.
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*/
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struct printk_buffers {
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char outbuf[PRINTK_MESSAGE_MAX];
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char scratchbuf[PRINTKRB_RECORD_MAX];
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};
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/**
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* struct printk_message - Container for a prepared printk message.
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* @pbufs: printk buffers used to prepare the message.
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* @outbuf_len: The length of prepared text in @pbufs->outbuf to output. This
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* does not count the terminator. A value of 0 means there is
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* nothing to output and this record should be skipped.
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* @seq: The sequence number of the record used for @pbufs->outbuf.
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* @dropped: The number of dropped records from reading @seq.
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*/
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struct printk_message {
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struct printk_buffers *pbufs;
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unsigned int outbuf_len;
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u64 seq;
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unsigned long dropped;
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};
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