m_copydata() with overlapping data?

[Sebastian Huber]

Hello,

I investigate currently a performance issue on a Microchip ATSAME70Q21 
(ARM Cortex-M7). The Newlib C-library has specialized routines for 
memcpy(), but not for memmove(). I noticed that m_copydata() uses 
bcopy() internally. According to the man page bcopy() is capable to deal 
with overlapping memory regions. Is this also a requirement for 
m_copydata() or could we use memcpy() here? For example:

diff --git a/freebsd/sys/kern/uipc_mbuf.c b/freebsd/sys/kern/uipc_mbuf.c
index 185d14a0..00dcd975 100644
--- a/freebsd/sys/kern/uipc_mbuf.c
+++ b/freebsd/sys/kern/uipc_mbuf.c
@@ -593,7 +593,7 @@ m_copydata(const struct mbuf *m, int off, int len, 
caddr_t cp)
         while (len > 0) {
                 KASSERT(m != NULL, ("m_copydata, length > size of mbuf 
chain"));
                 count = min(m->m_len - off, len);
-               bcopy(mtod(m, caddr_t) + off, cp, count);
+               cp = memcpy(cp, mtod(m, caddr_t) + off, count);
                 len -= count;
                 cp += count;
                 off = 0;

Maybe this should be mentioned in the man page:

https://www.freebsd.org/cgi/man.cgi?query=m_copydata

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber at embedded-brains.de
PGP     : Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.