Messages in this thread | | | From | John Ogness <> | Subject | Re: [PATCH v2] printk: ringbuffer: Improve prb_next_seq() performance | Date | Wed, 27 Oct 2021 17:54:42 +0206 |
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On 2021-10-27, Petr Mladek <pmladek@suse.com> wrote: > diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c > index 8a7b7362c0dd..24f47fbefbb5 100644 > --- a/kernel/printk/printk_ringbuffer.c > +++ b/kernel/printk/printk_ringbuffer.c > @@ -474,8 +474,10 @@ static enum desc_state desc_read(struct prb_desc_ring *desc_ring, > * state has been re-checked. A memcpy() for all of @desc > * cannot be used because of the atomic_t @state_var field. > */ > - memcpy(&desc_out->text_blk_lpos, &desc->text_blk_lpos, > - sizeof(desc_out->text_blk_lpos)); /* LMM(desc_read:C) */ > + if (desc_out) { > + memcpy(&desc_out->text_blk_lpos, &desc->text_blk_lpos, > + sizeof(desc_out->text_blk_lpos)); /* LMM(desc_read:C) */ > + } > if (seq_out) > *seq_out = info->seq; /* also part of desc_read:C */ > if (caller_id_out)
You also need this hunk:
@@ -530,7 +530,8 @@ static enum desc_state desc_read(struct prb_desc_ring *desc_ring, state_val = atomic_long_read(state_var); /* LMM(desc_read:E) */ d_state = get_desc_state(id, state_val); out: - atomic_long_set(&desc_out->state_var, state_val); + if (desc_out) + atomic_long_set(&desc_out->state_var, state_val); return d_state; }
Sorry, I missed it in my last review. This time I build+boot tested the patch.
With this hunk added:
Reviewed-by: John Ogness <john.ogness@linutronix.de>
John
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