git: 23204710f2b2 - main - unix: don't free the source mbuf in unp_externalize()

[Gleb Smirnoff]

The branch main has been updated by glebius:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=23204710f2b267ea396b53f81cc3b8b111d4aaf1

commit 23204710f2b267ea396b53f81cc3b8b111d4aaf1
Author:     Gleb Smirnoff <gleb...@freebsd.org>
AuthorDate: 2025-05-28 18:54:26 +0000
Commit:     Gleb Smirnoff <gleb...@freebsd.org>
CommitDate: 2025-05-29 18:44:52 +0000

    unix: don't free the source mbuf in unp_externalize()
    
    This makes calling the function simplier.
---
 sys/kern/uipc_usrreq.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/sys/kern/uipc_usrreq.c b/sys/kern/uipc_usrreq.c
index 19634e3916da..c411f22970e7 100644
--- a/sys/kern/uipc_usrreq.c
+++ b/sys/kern/uipc_usrreq.c
@@ -1526,8 +1526,6 @@ restart:
 
        while (control != NULL && control->m_type == MT_CONTROL) {
                if (!peek) {
-                       struct mbuf *c;
-
                        /*
                         * unp_externalize() failure must abort entire read(2).
                         * Such failure should also free the problematic
@@ -1537,14 +1535,9 @@ restart:
                         * Probability of such a failure is really low, so it
                         * is fine that we need to perform pretty complex
                         * operation here to reconstruct the buffer.
-                        * XXXGL: unp_externalize() used to be
-                        * dom_externalize() KBI and it frees whole chain, so
-                        * we need to feed it with mbufs one by one.
                         */
-                       c = control;
-                       control = STAILQ_NEXT(c, m_stailq);
-                       STAILQ_NEXT(c, m_stailq) = NULL;
-                       error = unp_externalize(c, controlp, flags);
+                       error = unp_externalize(control, controlp, flags);
+                       control = m_free(control);
                        if (__predict_false(error && control != NULL)) {
                                struct mchain cmc;
 
@@ -2322,13 +2315,8 @@ uipc_soreceive_dgram(struct socket *so, struct sockaddr 
**psa, struct uio *uio,
         * without MT_DATA mbufs.
         */
        while (m != NULL && m->m_type == MT_CONTROL) {
-               struct mbuf *cm;
-
-               /* XXXGL: unp_externalize() is also dom_externalize() KBI and
-                * it frees whole chain, so we must disconnect the mbuf.
-                */
-               cm = m; m = m->m_next; cm->m_next = NULL;
-               error = unp_externalize(cm, controlp, flags);
+               error = unp_externalize(m, controlp, flags);
+               m = m_free(m);
                if (error != 0) {
                        SOCK_IO_RECV_UNLOCK(so);
                        unp_scan(m, unp_freerights);
@@ -3541,7 +3529,6 @@ next:
                }
        }
 
-       m_freem(control);
        return (error);
 }