c4fcc617e1
Currently "dropped messages" are separately printed immediately before printing the printk message. Since normal consoles are now using an output buffer that is much larger than previously, the "dropped message" could be prepended to the printk message and then output everything in a single write() call. Introduce a helper function console_prepend_dropped() to prepend an existing message with a "dropped message". This simplifies the code by allowing all message formatting to be handled together and then only requires a single write() call to output the full message. And since this helper does not require any locking, it can be used in the future for other console printing contexts as well. Note that console_prepend_dropped() is defined as a NOP for !CONFIG_PRINTK. Although the function will never be called for !CONFIG_PRINTK, compiling the function can lead to warnings of "always true" conditionals due to the size macro values used in !CONFIG_PRINTK. 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/20230109100800.1085541-7-john.ogness@linutronix.de
107 lines
3.0 KiB
C
107 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 PREFIX_MAX 48
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#else
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#define PREFIX_MAX 32
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#endif
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/* the maximum size of a formatted record (i.e. with prefix added per line) */
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#define CONSOLE_LOG_MAX 1024
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/* the maximum size of a formatted extended record */
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#define CONSOLE_EXT_LOG_MAX 8192
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/* the maximum size allowed to be reserved for a record */
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#define LOG_LINE_MAX (CONSOLE_LOG_MAX - PREFIX_MAX)
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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 PREFIX_MAX 0
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#define CONSOLE_LOG_MAX 0
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#define CONSOLE_EXT_LOG_MAX 0
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#define LOG_LINE_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[CONSOLE_EXT_LOG_MAX];
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char scratchbuf[LOG_LINE_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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