This patch converts the rest of logbuf users (which are out of printk recursion case, but can deadlock in printk). To make printk-safe usage easier the patch introduces 4 helper macros: - logbuf_lock_irq()/logbuf_unlock_irq() lock/unlock the logbuf lock and disable/enable local IRQ
- logbuf_lock_irqsave(flags)/logbuf_unlock_irqrestore(flags) lock/unlock the logbuf lock and saves/restores local IRQ state Signed-off-by: Sergey Senozhatsky <[email protected]> --- kernel/printk/printk.c | 103 +++++++++++++++++++++++++++++++------------------ 1 file changed, 65 insertions(+), 38 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 1002dfd4ee96..75a944b3429f 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -370,6 +370,34 @@ __packed __aligned(4) */ DEFINE_RAW_SPINLOCK(logbuf_lock); +/* + * Helper macros to lock/unlock logbuf_lock and switch between + * printk-safe/unsafe modes. + */ +#define logbuf_lock_irq() \ + do { \ + printk_safe_enter_irq(); \ + raw_spin_lock(&logbuf_lock); \ + } while (0) + +#define logbuf_unlock_irq() \ + do { \ + raw_spin_unlock(&logbuf_lock); \ + printk_safe_exit_irq(); \ + } while (0) + +#define logbuf_lock_irqsave(flags) \ + do { \ + printk_safe_enter_irqsave(flags); \ + raw_spin_lock(&logbuf_lock); \ + } while (0) + +#define logbuf_unlock_irqrestore(flags) \ + do { \ + raw_spin_unlock(&logbuf_lock); \ + printk_safe_exit_irqrestore(flags); \ + } while (0) + #ifdef CONFIG_PRINTK DECLARE_WAIT_QUEUE_HEAD(log_wait); /* the next printk record to read by syslog(READ) or /proc/kmsg */ @@ -801,20 +829,21 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf, ret = mutex_lock_interruptible(&user->lock); if (ret) return ret; - raw_spin_lock_irq(&logbuf_lock); + + logbuf_lock_irq(); while (user->seq == log_next_seq) { if (file->f_flags & O_NONBLOCK) { ret = -EAGAIN; - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); goto out; } - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); ret = wait_event_interruptible(log_wait, user->seq != log_next_seq); if (ret) goto out; - raw_spin_lock_irq(&logbuf_lock); + logbuf_lock_irq(); } if (user->seq < log_first_seq) { @@ -822,7 +851,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf, user->idx = log_first_idx; user->seq = log_first_seq; ret = -EPIPE; - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); goto out; } @@ -835,7 +864,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf, user->idx = log_next(user->idx); user->seq++; - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); if (len > count) { ret = -EINVAL; @@ -862,7 +891,7 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) if (offset) return -ESPIPE; - raw_spin_lock_irq(&logbuf_lock); + logbuf_lock_irq(); switch (whence) { case SEEK_SET: /* the first record */ @@ -886,7 +915,7 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) default: ret = -EINVAL; } - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); return ret; } @@ -900,7 +929,7 @@ static unsigned int devkmsg_poll(struct file *file, poll_table *wait) poll_wait(file, &log_wait, wait); - raw_spin_lock_irq(&logbuf_lock); + logbuf_lock_irq(); if (user->seq < log_next_seq) { /* return error when data has vanished underneath us */ if (user->seq < log_first_seq) @@ -908,7 +937,7 @@ static unsigned int devkmsg_poll(struct file *file, poll_table *wait) else ret = POLLIN|POLLRDNORM; } - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); return ret; } @@ -938,10 +967,10 @@ static int devkmsg_open(struct inode *inode, struct file *file) mutex_init(&user->lock); - raw_spin_lock_irq(&logbuf_lock); + logbuf_lock_irq(); user->idx = log_first_idx; user->seq = log_first_seq; - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); file->private_data = user; return 0; @@ -1083,13 +1112,13 @@ void __init setup_log_buf(int early) return; } - raw_spin_lock_irqsave(&logbuf_lock, flags); + logbuf_lock_irqsave(flags); log_buf_len = new_log_buf_len; log_buf = new_log_buf; new_log_buf_len = 0; free = __LOG_BUF_LEN - log_next_idx; memcpy(log_buf, __log_buf, __LOG_BUF_LEN); - raw_spin_unlock_irqrestore(&logbuf_lock, flags); + logbuf_unlock_irqrestore(flags); pr_info("log_buf_len: %d bytes\n", log_buf_len); pr_info("early log buf free: %d(%d%%)\n", @@ -1267,7 +1296,7 @@ static int syslog_print(char __user *buf, int size) size_t n; size_t skip; - raw_spin_lock_irq(&logbuf_lock); + logbuf_lock_irq(); if (syslog_seq < log_first_seq) { /* messages are gone, move to first one */ syslog_seq = log_first_seq; @@ -1275,7 +1304,7 @@ static int syslog_print(char __user *buf, int size) syslog_partial = 0; } if (syslog_seq == log_next_seq) { - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); break; } @@ -1294,7 +1323,7 @@ static int syslog_print(char __user *buf, int size) syslog_partial += n; } else n = 0; - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); if (!n) break; @@ -1323,7 +1352,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear) if (!text) return -ENOMEM; - raw_spin_lock_irq(&logbuf_lock); + logbuf_lock_irq(); if (buf) { u64 next_seq; u64 seq; @@ -1371,12 +1400,12 @@ static int syslog_print_all(char __user *buf, int size, bool clear) idx = log_next(idx); seq++; - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); if (copy_to_user(buf + len, text, textlen)) len = -EFAULT; else len += textlen; - raw_spin_lock_irq(&logbuf_lock); + logbuf_lock_irq(); if (seq < log_first_seq) { /* messages are gone, move to next one */ @@ -1390,7 +1419,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear) clear_seq = log_next_seq; clear_idx = log_next_idx; } - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); kfree(text); return len; @@ -1477,7 +1506,7 @@ int do_syslog(int type, char __user *buf, int len, int source) break; /* Number of chars in the log buffer */ case SYSLOG_ACTION_SIZE_UNREAD: - raw_spin_lock_irq(&logbuf_lock); + logbuf_lock_irq(); if (syslog_seq < log_first_seq) { /* messages are gone, move to first one */ syslog_seq = log_first_seq; @@ -1505,7 +1534,7 @@ int do_syslog(int type, char __user *buf, int len, int source) } error -= syslog_partial; } - raw_spin_unlock_irq(&logbuf_lock); + logbuf_unlock_irq(); break; /* Size of the log buffer */ case SYSLOG_ACTION_SIZE_BUFFER: @@ -1681,9 +1710,8 @@ asmlinkage int vprintk_emit(int facility, int level, boot_delay_msec(level); printk_delay(); - printk_safe_enter_irqsave(flags); /* This stops the holder of console_sem just where we want him */ - raw_spin_lock(&logbuf_lock); + logbuf_lock_irqsave(flags); /* * The printf needs to come first; we need the syslog * prefix which might be passed-in as a parameter. @@ -1726,8 +1754,7 @@ asmlinkage int vprintk_emit(int facility, int level, printed_len += log_output(facility, level, lflags, dict, dictlen, text, text_len); - raw_spin_unlock(&logbuf_lock); - printk_safe_exit_irqrestore(flags); + logbuf_unlock_irqrestore(flags); /* If called from the scheduler, we can not call up(). */ if (!in_sched) { @@ -2500,10 +2527,10 @@ void register_console(struct console *newcon) * console_unlock(); will print out the buffered messages * for us. */ - raw_spin_lock_irqsave(&logbuf_lock, flags); + logbuf_lock_irqsave(flags); console_seq = syslog_seq; console_idx = syslog_idx; - raw_spin_unlock_irqrestore(&logbuf_lock, flags); + logbuf_unlock_irqrestore(flags); /* * We're about to replay the log buffer. Only do this to the * just-registered console to avoid excessive message spam to @@ -2802,12 +2829,12 @@ void kmsg_dump(enum kmsg_dump_reason reason) /* initialize iterator with data about the stored records */ dumper->active = true; - raw_spin_lock_irqsave(&logbuf_lock, flags); + logbuf_lock_irqsave(flags); dumper->cur_seq = clear_seq; dumper->cur_idx = clear_idx; dumper->next_seq = log_next_seq; dumper->next_idx = log_next_idx; - raw_spin_unlock_irqrestore(&logbuf_lock, flags); + logbuf_unlock_irqrestore(flags); /* invoke dumper which will iterate over records */ dumper->dump(dumper, reason); @@ -2892,9 +2919,9 @@ bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, unsigned long flags; bool ret; - raw_spin_lock_irqsave(&logbuf_lock, flags); + logbuf_lock_irqsave(flags); ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); - raw_spin_unlock_irqrestore(&logbuf_lock, flags); + logbuf_unlock_irqrestore(flags); return ret; } @@ -2933,7 +2960,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, if (!dumper->active) goto out; - raw_spin_lock_irqsave(&logbuf_lock, flags); + logbuf_lock_irqsave(flags); if (dumper->cur_seq < log_first_seq) { /* messages are gone, move to first available one */ dumper->cur_seq = log_first_seq; @@ -2942,7 +2969,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, /* last entry */ if (dumper->cur_seq >= dumper->next_seq) { - raw_spin_unlock_irqrestore(&logbuf_lock, flags); + logbuf_unlock_irqrestore(flags); goto out; } @@ -2984,7 +3011,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, dumper->next_seq = next_seq; dumper->next_idx = next_idx; ret = true; - raw_spin_unlock_irqrestore(&logbuf_lock, flags); + logbuf_unlock_irqrestore(flags); out: if (len) *len = l; @@ -3022,9 +3049,9 @@ void kmsg_dump_rewind(struct kmsg_dumper *dumper) { unsigned long flags; - raw_spin_lock_irqsave(&logbuf_lock, flags); + logbuf_lock_irqsave(flags); kmsg_dump_rewind_nolock(dumper); - raw_spin_unlock_irqrestore(&logbuf_lock, flags); + logbuf_unlock_irqrestore(flags); } EXPORT_SYMBOL_GPL(kmsg_dump_rewind); -- 2.11.0
