Messages in this thread Patch in this message | | | From | John Ogness <> | Subject | [PATCH printk v2 5/7] printk: Use struct console_buffers | Date | Thu, 24 Nov 2022 00:19:58 +0106 |
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From: Thomas Gleixner <tglx@linutronix.de>
Replace the separately allocated output buffers with a single instance of struct console_buffers.
Note that the buffer size of devkmsg_user.text_buf, when replaced with console_buffers.text, reduces from CONSOLE_EXT_LOG_MAX to CONSOLE_LOG_MAX. However, the buffer is only used to read ringbuffer records. These records have a maximum size of LOG_LINE_MAX, which is defined as CONSOLE_LOG_MAX - PREFIX_MAX.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> --- kernel/printk/printk.c | 68 ++++++++++++++++++++---------------------- 1 file changed, 32 insertions(+), 36 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index a4854a60e6d8..750559171e30 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -712,11 +712,9 @@ struct devkmsg_user { atomic64_t seq; struct ratelimit_state rs; struct mutex lock; - char buf[CONSOLE_EXT_LOG_MAX]; - struct printk_info info; - char text_buf[CONSOLE_EXT_LOG_MAX]; struct printk_record record; + struct console_buffers cbufs; }; static __printf(3, 4) __cold @@ -798,6 +796,8 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { struct devkmsg_user *user = file->private_data; + const int ext_text_size = sizeof(user->cbufs.ext_text); + char *ext_text = &user->cbufs.ext_text[0]; struct printk_record *r = &user->record; size_t len; ssize_t ret; @@ -839,8 +839,8 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf, goto out; } - len = info_print_ext_header(user->buf, sizeof(user->buf), r->info); - len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, + len = info_print_ext_header(ext_text, ext_text_size, r->info); + len += msg_print_ext_body(ext_text + len, ext_text_size - len, &r->text_buf[0], r->info->text_len, &r->info->dev_info); @@ -851,7 +851,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf, goto out; } - if (copy_to_user(buf, user->buf, len)) { + if (copy_to_user(buf, ext_text, len)) { ret = -EFAULT; goto out; } @@ -950,7 +950,7 @@ static int devkmsg_open(struct inode *inode, struct file *file) mutex_init(&user->lock); prb_rec_init_rd(&user->record, &user->info, - &user->text_buf[0], sizeof(user->text_buf)); + &user->cbufs.text[0], sizeof(user->cbufs.text)); atomic64_set(&user->seq, prb_first_valid_seq(prb)); @@ -2007,6 +2007,10 @@ static int console_trylock_spinning(void) return 1; } +#if DROPPED_TEXT_MAX > CONSOLE_EXT_LOG_MAX +#error "DROPPED_TEXT_MAX too large for console_buffers->ext_text" +#endif + /* * Call the specified console driver, asking it to write out the specified * text and length. If @dropped_text is non-NULL and any records have been @@ -2741,36 +2745,32 @@ static void __console_unlock(void) * Print one record for the given console. The record printed is whatever * record is the next available record for the given console. * - * @text is a buffer of size CONSOLE_LOG_MAX. + * @cbufs is the console buffers used to string-print the formatted messages. * - * If extended messages should be printed, @ext_text is a buffer of size - * CONSOLE_EXT_LOG_MAX. Otherwise @ext_text must be NULL. - * - * If dropped messages should be printed, @dropped_text is a buffer of size - * DROPPED_TEXT_MAX. Otherwise @dropped_text must be NULL. + * @cookie is the cookie from entering the SRCU read-side critical section. * * @handover will be set to true if a printk waiter has taken over the * console_lock, in which case the caller is no longer holding both the * console_lock and the SRCU read lock. Otherwise it is set to false. * - * @cookie is the cookie from the SRCU read lock. - * * Returns false if the given console has no next record to print, otherwise * true. * * Requires the console_lock and the SRCU read lock. */ -static bool console_emit_next_record(struct console *con, char *text, char *ext_text, - char *dropped_text, bool *handover, int cookie) +static bool console_emit_next_record(struct console *con, struct console_buffers *cbufs, + int cookie, bool *handover) { static int panic_console_dropped; struct printk_info info; struct printk_record r; + size_t write_text_size; unsigned long flags; + char *dropped_text; char *write_text; size_t len; - prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); + prb_rec_init_rd(&r, &info, &cbufs->text[0], sizeof(cbufs->text)); *handover = false; @@ -2792,13 +2792,20 @@ static bool console_emit_next_record(struct console *con, char *text, char *ext_ goto skip; } - if (ext_text) { - write_text = ext_text; - len = info_print_ext_header(ext_text, CONSOLE_EXT_LOG_MAX, r.info); - len += msg_print_ext_body(ext_text + len, CONSOLE_EXT_LOG_MAX - len, + if (console_srcu_read_flags(con) & CON_EXTENDED) { + /* Extended consoles do not print "dropped messages". */ + dropped_text = NULL; + + write_text = &cbufs->ext_text[0]; + write_text_size = sizeof(cbufs->ext_text); + len = info_print_ext_header(write_text, write_text_size, r.info); + len += msg_print_ext_body(write_text + len, write_text_size - len, &r.text_buf[0], r.info->text_len, &r.info->dev_info); } else { - write_text = text; + /* @ext_text is unused. Use it for "dropped messages". */ + dropped_text = &cbufs->ext_text[0]; + + write_text = &cbufs->text[0]; len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time); } @@ -2852,9 +2859,7 @@ static bool console_emit_next_record(struct console *con, char *text, char *ext_ */ static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handover) { - static char dropped_text[DROPPED_TEXT_MAX]; - static char ext_text[CONSOLE_EXT_LOG_MAX]; - static char text[CONSOLE_LOG_MAX]; + static struct console_buffers cbufs; bool any_usable = false; struct console *con; bool any_progress; @@ -2874,16 +2879,7 @@ static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handove continue; any_usable = true; - if (console_srcu_read_flags(con) & CON_EXTENDED) { - /* Extended consoles do not print "dropped messages". */ - progress = console_emit_next_record(con, &text[0], - &ext_text[0], NULL, - handover, cookie); - } else { - progress = console_emit_next_record(con, &text[0], - NULL, &dropped_text[0], - handover, cookie); - } + progress = console_emit_next_record(con, &cbufs, cookie, handover); /* * If a handover has occurred, the SRCU read lock -- 2.30.2
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