Re: [PATCH v5 27/32] PCI/P2PDMA: Convert to printbuf
From: Kent Overstreet
Date: Mon Aug 08 2022 - 14:42:57 EST
On 8/8/22 13:51, Bjorn Helgaas wrote:
I don't object to the patch, but it would be nice if the commit log
hinted at what the advantage is. I assume it's faster/safer/better in
some way, but I have no idea what.
Printbufs have some additional features over seq_buf but they're not
used here. The main one you might be interested in is heap allocation:
that means no need to statically allocate buffers on the stack and no
need to calculate the buffer size, printbufs will reallocate as necessary.
I generally haven't been converting code to use that unless it's obvious
that we're in a context where it's safe to allocate memory and can deal
with allocation failures.
I notice that in calc_map_type_and_dist() you're using xa_store() which
can fail, but you're not checking for that or returning errors properly
:) perhaps a fix for that could also switch to using printbuf in
heap-allocation mode.
Also, cpu_show_meltdown() doesn't appear in this patch, so maybe
that's relevant to some other patch but not this one?
Whoops, was copying the commit message from another patch, yeah.n