[Devel] [PATCH rh9 03/11] ve/printk: Virtualize syslog_*
Kirill Tkhai
ktkhai at virtuozzo.com
Thu Sep 30 13:49:16 MSK 2021
On 29.09.2021 22:24, Konstantin Khorenko wrote:
> From: Vladimir Davydov <vdavydov at parallels.com>
>
> https://jira.sw.ru/browse/PSBM-17899
>
> Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
> Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
>
> +++
> ve/printk: Fix printk virtualization
>
> ve_printk() corrupts host's dmesg:
> # dmesg|wc -l
> 599
> # vzctl create 101
> # vzctl set 101 --netif_add eth0 --save
> # vzctl start 101
> # vzctl exec 101 'tcpdump -w tcpdump.out -U -n -i eth0 esp'
> # dmesg|wc -l
> 2
>
> Add missing parts of prinkt virtualization to fix this.
>
> https://jira.sw.ru/browse/PSBM-17899
> https://jira.sw.ru/browse/PSBM-105442
>
> Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
>
> Rebasing to vz9: part of vz8 commit:
> d63aeb311a64 ("ve/printk: printk virtualization")
>
> https://jira.sw.ru/browse/PSBM-133985
>
> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
> ---
> kernel/printk/printk.c | 60 +++++++++++++++++++++---------------------
> 1 file changed, 30 insertions(+), 30 deletions(-)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index a1dedbc88426..70dbf204c052 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -360,13 +360,6 @@ enum log_flags {
> static DEFINE_RAW_SPINLOCK(syslog_lock);
>
> #ifdef CONFIG_PRINTK
> -DECLARE_WAIT_QUEUE_HEAD(log_wait);
log_wait is still used in code, so we should move this to another patch.
> -/* All 3 protected by @syslog_lock. */
> -/* the next printk record to read by syslog(READ) or /proc/kmsg */
> -static u64 syslog_seq;
> -static size_t syslog_partial;
> -static bool syslog_time;
> -
> /* All 3 protected by @console_sem. */
> /* the next printk record to write to the console */
> static u64 console_seq;
> @@ -418,6 +411,12 @@ static struct log_state {
> char *buf;
> u32 buf_len;
>
> + /* All 3 protected by @syslog_lock. */
> + /* the next printk record to read by syslog(READ) or /proc/kmsg */
> + u64 syslog_seq;
> + size_t syslog_partial;
> + bool syslog_time;
> +
> /*
> * The next printk record to read after the last 'clear' command. There are
> * two copies (updated with seqcount_latch) so that reads can locklessly
> @@ -1546,35 +1545,35 @@ static int syslog_print(struct log_state *log,
>
> printk_safe_enter_irq();
> raw_spin_lock(&syslog_lock);
> - if (!prb_read_valid(log->prb, syslog_seq, &r)) {
> + if (!prb_read_valid(log->prb, log->syslog_seq, &r)) {
> raw_spin_unlock(&syslog_lock);
> printk_safe_exit_irq();
> break;
> }
> - if (r.info->seq != syslog_seq) {
> + if (r.info->seq != log->syslog_seq) {
> /* message is gone, move to next valid one */
> - syslog_seq = r.info->seq;
> - syslog_partial = 0;
> + log->syslog_seq = r.info->seq;
> + log->syslog_partial = 0;
> }
>
> /*
> * To keep reading/counting partial line consistent,
> * use printk_time value as of the beginning of a line.
> */
> - if (!syslog_partial)
> - syslog_time = printk_time;
> + if (!log->syslog_partial)
> + log->syslog_time = printk_time;
>
> - skip = syslog_partial;
> - n = record_print_text(&r, true, syslog_time);
> - if (n - syslog_partial <= size) {
> + skip = log->syslog_partial;
> + n = record_print_text(&r, true, log->syslog_time);
> + if (n - log->syslog_partial <= size) {
> /* message fits into buffer, move forward */
> - syslog_seq = r.info->seq + 1;
> - n -= syslog_partial;
> - syslog_partial = 0;
> + log->syslog_seq = r.info->seq + 1;
> + n -= log->syslog_partial;
> + log->syslog_partial = 0;
> } else if (!len){
> /* partial read(), remember position */
> n = size;
> - syslog_partial += n;
> + log->syslog_partial += n;
> } else
> n = 0;
> raw_spin_unlock(&syslog_lock);
> @@ -1669,10 +1668,11 @@ static void syslog_clear(struct log_state *log)
> /* Return a consistent copy of @syslog_seq. */
> static u64 read_syslog_seq_irq(void)
> {
> + struct log_state *log = ve_log_state();
> u64 seq;
>
> raw_spin_lock_irq(&syslog_lock);
> - seq = syslog_seq;
> + seq = log->syslog_seq;
> raw_spin_unlock_irq(&syslog_lock);
>
> return seq;
> @@ -1707,7 +1707,7 @@ int do_syslog(int type, char __user *buf, int len, int source)
> prb_read_valid(log->prb, read_syslog_seq_irq(), NULL));
> if (error)
> return error;
> - error = syslog_print(buf, len);
> + error = syslog_print(log, buf, len);
> break;
> /* Read/clear last kernel messages */
> case SYSLOG_ACTION_READ_CLEAR:
> @@ -1760,10 +1760,10 @@ int do_syslog(int type, char __user *buf, int len, int source)
> printk_safe_exit_irq();
> return 0;
> }
> - if (info.seq != syslog_seq) {
> + if (info.seq != log->syslog_seq) {
> /* messages are gone, move to first one */
> - syslog_seq = info.seq;
> - syslog_partial = 0;
> + log->syslog_seq = info.seq;
> + log->syslog_partial = 0;
> }
> if (source == SYSLOG_FROM_PROC) {
> /*
> @@ -1771,9 +1771,9 @@ int do_syslog(int type, char __user *buf, int len, int source)
> * for pending data, not the size; return the count of
> * records, not the length.
> */
> - error = prb_next_seq(log->prb) - syslog_seq;
> + error = prb_next_seq(log->prb) - log->syslog_seq;
> } else {
> - bool time = syslog_partial ? syslog_time : printk_time;
> + bool time = log->syslog_partial ? log->syslog_time : printk_time;
> unsigned int line_count;
> u64 seq;
>
> @@ -1783,7 +1783,7 @@ int do_syslog(int type, char __user *buf, int len, int source)
> true, time);
> time = printk_time;
> }
> - error -= syslog_partial;
> + error -= log->syslog_partial;
> }
> raw_spin_unlock(&syslog_lock);
> printk_safe_exit_irq();
> @@ -2301,7 +2301,6 @@ EXPORT_SYMBOL(printk);
> #define prb_read_valid(rb, seq, r) false
> #define prb_first_valid_seq(rb) 0
>
> -static u64 syslog_seq;
> static u64 console_seq;
> static u64 exclusive_console_stop_seq;
> static unsigned long console_dropped;
> @@ -2945,6 +2944,7 @@ static int try_enable_new_console(struct console *newcon, bool user_specified)
> */
> void register_console(struct console *newcon)
> {
> + struct log_state *log = &init_log_state;
> unsigned long flags;
> struct console *bcon = NULL;
> int err;
> @@ -3051,7 +3051,7 @@ void register_console(struct console *newcon)
>
> /* Get a consistent copy of @syslog_seq. */
> raw_spin_lock_irqsave(&syslog_lock, flags);
> - console_seq = syslog_seq;
> + console_seq = log->syslog_seq;
> raw_spin_unlock_irqrestore(&syslog_lock, flags);
> }
> console_unlock();
>
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