Messages in this thread | | | Date | Thu, 1 Dec 2016 10:08:48 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [RFC][PATCHv4 3/6] printk: introduce per-cpu safe_print seq buffer |
| |
On (11/24/16 17:58), Petr Mladek wrote: [..] > > +#ifdef CONFIG_PRINTK > > + > > +#define PRINTK_SAFE_CONTEXT_MASK 0x7fffffff > > +#define PRINTK_SAFE_NMI_CONTEXT_MASK 0x80000000 > > What about shorter name PRINTK_NMI_CONTEXT_MASK?
ok.
> > diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c > > index 1f66163..af74d9c 100644 > > --- a/kernel/printk/printk_safe.c > > +++ b/kernel/printk/printk_safe.c > > @@ -50,27 +49,26 @@ struct printk_safe_seq_buf { > > struct irq_work work; /* IRQ work that flushes the buffer */ > > unsigned char buffer[SAFE_LOG_BUF_LEN]; > > }; > > + > > +static DEFINE_PER_CPU(struct printk_safe_seq_buf, safe_print_seq); > > +static DEFINE_PER_CPU(int, printk_safe_context); > > I would personally use the short name "printk_context". It is a generic > value. Zero value means that it is a normal context. Also there is > an idea to add KDB context that would use its own vprintk_kdb() > implementation and will not use the printk_safe buffer.
ok.
> > - if (len >= sizeof(s->buffer)) { > > - atomic_inc(&nmi_message_lost); > > - return 0; > > - } > > + if (len >= sizeof(s->buffer)) > > + return -E2BIG; > > E2BIG means "argument list too long" and does not fit much here. > I would suggest to use -ENOSPC. It is not ideal either but it fits > slightly better.
ok.
> > +/* > > + * Lockless printk(), to avoid deadlocks should the printk() recurse > > + * into itself. It uses a per-CPU buffer to store the message, just like > > + * NMI. > > + */ > > +static int vprintk_safe(const char *fmt, va_list args) > > +{ > > + struct printk_safe_seq_buf *s = this_cpu_ptr(&safe_print_seq); > > + > > + return printk_safe_log_store(s, fmt, args); > > We should return zero if printk_safe_log_store() returns an error. > I know that it will get fixed in the next patch. But we should do > some minimum sanity check here because of bisection.
ok.
-ss
| |