On (20/12/07 10:50), Petr Mladek wrote:
[..]
> > and then some call into the scheduler
> > (or other kernel core functions) under semaphore's spin_lock.
> > For instance
> >
> > up()
> > raw_spin_lock_irqsave(&sem->lock)
> >__up()
> > wake_up_process()
> >try_
On Sun 2020-12-06 23:36:53, John Ogness wrote:
> On 2020-12-04, Petr Mladek wrote:
> >> + if (facility == 0) {
> >> + while (text_len >= 2 && printk_get_level(text)) {
> >> + text_len -= 2;
> >> + text += 2;
> >> + }
> >
> > We should avoid two
On Sun 2020-12-06 22:50:54, John Ogness wrote:
> On 2020-12-04, Petr Mladek wrote:
> > On Tue 2020-12-01 21:59:41, John Ogness wrote:
> >> Since the ringbuffer is lockless, there is no need for it to be
> >> protected by @logbuf_lock. Remove @logbuf_lock.
> >>
> >> --- a/kernel/printk/printk.c
>
On Sun 2020-12-06 22:12:21, John Ogness wrote:
> On 2020-12-04, Petr Mladek wrote:
> > On Tue 2020-12-01 21:59:41, John Ogness wrote:
> >> Since the ringbuffer is lockless, there is no need for it to be
> >> protected by @logbuf_lock. Remove @logbuf_lock.
> >>
> >> --- a/kernel/printk/printk.c
>
On Sun 2020-12-06 21:57:46, John Ogness wrote:
> On 2020-12-04, Petr Mladek wrote:
> >> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> >> index e9018c4e1b66..7385101210be 100644
> >> --- a/kernel/printk/printk.c
> >> +++ b/kernel/printk/printk.c
> >> @@ -785,7 +749,6 @@ static loff
On Sat 2020-12-05 13:39:53, Sergey Senozhatsky wrote:
> On (20/12/04 17:19), Petr Mladek wrote:
> [..]
> > > --- a/kernel/printk/printk.c
> > > +++ b/kernel/printk/printk.c
> > > @@ -2432,7 +2490,6 @@ void console_unlock(void)
> > > size_t len;
> > >
> > > printk_safe_enter_ir
On 2020-12-04, Petr Mladek wrote:
>> +/* Strip kernel syslog prefix. */
>
> Syslog actually uses: format. We are skipping log level
> and control flags here.
OK.
>> +if (facility == 0) {
>> +while (text_len >= 2 && printk_get_level(text)) {
>> +text_len -
On 2020-12-05, Sergey Senozhatsky wrote:
>> One reason is the use of per-cpu variables. Alternative solution would
>> be to store printk_context into task_struct.
>
> We can keep per-CPU, disable preemption and have counters for
> every context (task, soft/hard irq, NMI). Shouldn't be a problem
T
On 2020-12-05, Sergey Senozhatsky wrote:
>> We should allow at least some level of recursion. Otherwise, we would
>> not see warnings printed from vsprintf code.
>
> One level of recursion seems reasonable on one hand, but on the other
> hand I also wonder if we can get useful info from recursion
On 2020-12-04, Petr Mladek wrote:
> On Tue 2020-12-01 21:59:41, John Ogness wrote:
>> Since the ringbuffer is lockless, there is no need for it to be
>> protected by @logbuf_lock. Remove @logbuf_lock.
>>
>> --- a/kernel/printk/printk.c
>> +++ b/kernel/printk/printk.c
>> @@ -1847,6 +1811,65 @@ sta
On 2020-12-04, Petr Mladek wrote:
> On Tue 2020-12-01 21:59:41, John Ogness wrote:
>> Since the ringbuffer is lockless, there is no need for it to be
>> protected by @logbuf_lock. Remove @logbuf_lock.
>>
>> --- a/kernel/printk/printk.c
>> +++ b/kernel/printk/printk.c
>> @@ -1490,19 +1444,30 @@ st
On 2020-12-04, Petr Mladek wrote:
>> Since the ringbuffer is lockless, there is no need for it to be
>> protected by @logbuf_lock. Remove @logbuf_lock.
>
> It might make sense to split also this patch into few more pieces that
> would remove the lock from a particular interface.
OK.
>> diff --gi
On 2020-12-04, Sergey Senozhatsky wrote:
>> +static char *get_printk_count(void)
>
> A nit: I think get_foo() has some sort of special meaning and one
> would expect that there should be put_foo() as well, and that those
> have something to do with the ref counting.
OK. How about:
static char *p
On (20/12/04 17:10), Petr Mladek wrote:
>
> One reason is the use of per-cpu variables. Alternative solution would
> be to store printk_context into task_struct.
We can keep per-CPU, disable preemption and have counters for
every context (task, soft/hard irq, NMI). Shouldn't be a problem
On (20/12/04 17:19), Petr Mladek wrote:
[..]
> > --- a/kernel/printk/printk.c
> > +++ b/kernel/printk/printk.c
> > @@ -2432,7 +2490,6 @@ void console_unlock(void)
> > size_t len;
> >
> > printk_safe_enter_irqsave(flags);
>
> Why do we actually need to use the printk_safe
On (20/12/04 17:10), Petr Mladek wrote:
[..]
> char *get_printk_counter_by_ctx()
> {
> int ctx = 0;
>
> if (in_nmi)
> ctx = 1;
>
> if (!printk_percpu_data_ready())
> return &printk_count_early[ctx];
>
> return this_cpu_ptr(printk_count[ctx]);
>
On Tue 2020-12-01 21:59:41, John Ogness wrote:
> Since the ringbuffer is lockless, there is no need for it to be
> protected by @logbuf_lock. Remove @logbuf_lock.
>
> --- a/kernel/printk/internal.h
> +++ b/kernel/printk/internal.h
> @@ -59,7 +57,7 @@ void defer_console_output(void);
> __printf(1,
On Tue 2020-12-01 21:59:41, John Ogness wrote:
> Since the ringbuffer is lockless, there is no need for it to be
> protected by @logbuf_lock. Remove @logbuf_lock.
>
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1867,40 +1890,75 @@ static inline u32 printk_caller_id(void)
>
On Tue 2020-12-01 21:59:41, John Ogness wrote:
> Since the ringbuffer is lockless, there is no need for it to be
> protected by @logbuf_lock. Remove @logbuf_lock.
>
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1847,6 +1811,65 @@ static void call_console_drivers(const char *e
On Tue 2020-12-01 21:59:41, John Ogness wrote:
> Since the ringbuffer is lockless, there is no need for it to be
> protected by @logbuf_lock. Remove @logbuf_lock.
>
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1490,19 +1444,30 @@ static int syslog_print_all(char __user *buf,
On Tue 2020-12-01 21:59:41, John Ogness wrote:
> Since the ringbuffer is lockless, there is no need for it to be
> protected by @logbuf_lock. Remove @logbuf_lock.
I am going to split the feedback into few mails. It might make sense
to split also this patch into few more pieces that would remove th
On (20/12/01 21:59), John Ogness wrote:
>
> +#ifdef CONFIG_PRINTK_NMI
> +#define NUM_RECURSION_CTX 2
> +#else
> +#define NUM_RECURSION_CTX 1
> +#endif
> +
> +struct printk_recursion {
> + charcount[NUM_RECURSION_CTX];
> +};
> +
> +static DEFINE_PER_CPU(struct printk_recursion, percpu_prin
Since the ringbuffer is lockless, there is no need for it to be
protected by @logbuf_lock. Remove @logbuf_lock.
This means that printk_nmi_direct and printk_safe_flush_on_panic()
no longer need to acquire any lock to run.
The global variables @syslog_seq, @syslog_partial, @syslog_time
were also p
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