On 2020-09-23, Petr Mladek <[email protected]> wrote: >> After copying all records to the dynamic ringbuffer, setup_log_buf() >> checks to see if any records were dropped during the switch. However, >> it needs to check before enabling interrupts since new records could >> arrive in an interrupt, thus causing setup_log_buf() to erroneously >> think that it had dropped messages. > > Have you seen the problem, please? > >> Signed-off-by: John Ogness <[email protected]> >> --- >> kernel/printk/printk.c | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c >> index 1fe3d0cb2fe0..00bc1fce3299 100644 >> --- a/kernel/printk/printk.c >> +++ b/kernel/printk/printk.c >> @@ -1181,12 +1181,12 @@ void __init setup_log_buf(int early) >> */ >> prb = &printk_rb_dynamic; >> >> + seq = prb_next_seq(&printk_rb_static) - seq; >> + >> logbuf_unlock_irqrestore(flags); >> >> - if (seq != prb_next_seq(&printk_rb_static)) { > > I can't see how these two values could get modified after enabling interrupts. > > + @seq is set in the for-cycle before the interrupts are enabled. > > + @prb is updated before the interrupts are enabled. So that > the static buffer should not longer be used after that.
You are correct. This patch should be disregarded. John Ogness
