git: b93e930ca233 - main - sendfile: retire M_BLOCKED
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Date: Fri, 25 Jul 2025 20:06:50 UTC
The branch main has been updated by glebius:
URL: https://cgit.FreeBSD.org/src/commit/?id=b93e930ca233e3b3cb5e017bc9b09086f8909800
commit b93e930ca233e3b3cb5e017bc9b09086f8909800
Author: Gleb Smirnoff <glebius@FreeBSD.org>
AuthorDate: 2025-07-25 20:06:28 +0000
Commit: Gleb Smirnoff <glebius@FreeBSD.org>
CommitDate: 2025-07-25 20:06:28 +0000
sendfile: retire M_BLOCKED
Follow unix(4) commit 51ac5ee0d57f and retire M_BLOCKED for TCP sockets as
well. The M_BLOCKED flag was introduced back 2016 together with non-
blocking sendfile(2). It marked mbufs in a sending socket buffer that
could be ready to sent, but are sitting behind an M_NOTREADY mbuf(s), that
blocks them.
You may consider this flag as an INVARIANT flag that helped to ensure
socket buffer consistency. Or maybe the socket code was so convoluted
back then, that it was unclear if sbfree() may be called on an mbuf that
is in the middle of the buffer, and I decided to introduce the flag to
protect against that. With today state of socket buffer code it became
clear that the latter cannot happen. And this commit adds an assertion
proving that.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D50728
---
sys/dev/cxgbe/tom/t4_cpl_io.c | 6 +++---
sys/dev/cxgbe/tom/t4_tls.c | 4 ++--
sys/kern/uipc_ktls.c | 2 +-
sys/kern/uipc_sockbuf.c | 42 +++++++++++++++---------------------------
sys/kern/uipc_socket.c | 2 +-
sys/sys/sockbuf.h | 2 --
6 files changed, 22 insertions(+), 36 deletions(-)
diff --git a/sys/dev/cxgbe/tom/t4_cpl_io.c b/sys/dev/cxgbe/tom/t4_cpl_io.c
index 8547f21586e1..7a6b1cbdd736 100644
--- a/sys/dev/cxgbe/tom/t4_cpl_io.c
+++ b/sys/dev/cxgbe/tom/t4_cpl_io.c
@@ -703,7 +703,7 @@ t4_push_frames(struct adapter *sc, struct toepcb *toep, int drop)
for (m = sndptr; m != NULL; m = m->m_next) {
int n;
- if ((m->m_flags & M_NOTAVAIL) != 0)
+ if ((m->m_flags & M_NOTREADY) != 0)
break;
if (m->m_flags & M_EXTPG) {
#ifdef KERN_TLS
@@ -787,7 +787,7 @@ t4_push_frames(struct adapter *sc, struct toepcb *toep, int drop)
/* nothing to send */
if (plen == 0) {
- KASSERT(m == NULL || (m->m_flags & M_NOTAVAIL) != 0,
+ KASSERT(m == NULL || (m->m_flags & M_NOTREADY) != 0,
("%s: nothing to send, but m != NULL is ready",
__func__));
break;
@@ -880,7 +880,7 @@ t4_push_frames(struct adapter *sc, struct toepcb *toep, int drop)
toep->txsd_avail--;
t4_l2t_send(sc, wr, toep->l2te);
- } while (m != NULL && (m->m_flags & M_NOTAVAIL) == 0);
+ } while (m != NULL && (m->m_flags & M_NOTREADY) == 0);
/* Send a FIN if requested, but only if there's no more data to send */
if (m == NULL && toep->flags & TPF_SEND_FIN)
diff --git a/sys/dev/cxgbe/tom/t4_tls.c b/sys/dev/cxgbe/tom/t4_tls.c
index c6377980fca9..27c16b9988ae 100644
--- a/sys/dev/cxgbe/tom/t4_tls.c
+++ b/sys/dev/cxgbe/tom/t4_tls.c
@@ -563,7 +563,7 @@ t4_push_ktls(struct adapter *sc, struct toepcb *toep, int drop)
* If there is no ready data to send, wait until more
* data arrives.
*/
- if (m == NULL || (m->m_flags & M_NOTAVAIL) != 0) {
+ if (m == NULL || (m->m_flags & M_NOTREADY) != 0) {
if (sowwakeup)
sowwakeup_locked(so);
else
@@ -614,7 +614,7 @@ t4_push_ktls(struct adapter *sc, struct toepcb *toep, int drop)
/* Shove if there is no additional data pending. */
shove = ((m->m_next == NULL ||
- (m->m_next->m_flags & M_NOTAVAIL) != 0)) &&
+ (m->m_next->m_flags & M_NOTREADY) != 0)) &&
(tp->t_flags & TF_MORETOCOME) == 0;
if (sb->sb_flags & SB_AUTOSIZE &&
diff --git a/sys/kern/uipc_ktls.c b/sys/kern/uipc_ktls.c
index ce09042abdac..66ce1b5a081d 100644
--- a/sys/kern/uipc_ktls.c
+++ b/sys/kern/uipc_ktls.c
@@ -1207,7 +1207,7 @@ sb_mark_notready(struct sockbuf *sb)
for (; m != NULL; m = m->m_next) {
KASSERT(m->m_nextpkt == NULL, ("%s: m_nextpkt != NULL",
__func__));
- KASSERT((m->m_flags & M_NOTAVAIL) == 0, ("%s: mbuf not avail",
+ KASSERT((m->m_flags & M_NOTREADY) == 0, ("%s: mbuf not ready",
__func__));
KASSERT(sb->sb_acc >= m->m_len, ("%s: sb_acc < m->m_len",
__func__));
diff --git a/sys/kern/uipc_sockbuf.c b/sys/kern/uipc_sockbuf.c
index ffaa9b800592..745702bd4a4f 100644
--- a/sys/kern/uipc_sockbuf.c
+++ b/sys/kern/uipc_sockbuf.c
@@ -195,14 +195,14 @@ int
sbready(struct sockbuf *sb, struct mbuf *m0, int count)
{
struct mbuf *m;
- u_int blocker;
+ bool blocker;
SOCKBUF_LOCK_ASSERT(sb);
KASSERT(sb->sb_fnrdy != NULL, ("%s: sb %p NULL fnrdy", __func__, sb));
KASSERT(count > 0, ("%s: invalid count %d", __func__, count));
m = m0;
- blocker = (sb->sb_fnrdy == m) ? M_BLOCKED : 0;
+ blocker = (sb->sb_fnrdy == m);
while (count > 0) {
KASSERT(m->m_flags & M_NOTREADY,
@@ -217,8 +217,7 @@ sbready(struct sockbuf *sb, struct mbuf *m0, int count)
m->m_epg_nrdy = 0;
} else
count--;
-
- m->m_flags &= ~(M_NOTREADY | blocker);
+ m->m_flags &= ~M_NOTREADY;
if (blocker)
sb->sb_acc += m->m_len;
m = m->m_next;
@@ -240,12 +239,8 @@ sbready(struct sockbuf *sb, struct mbuf *m0, int count)
}
/* This one was blocking all the queue. */
- for (; m && (m->m_flags & M_NOTREADY) == 0; m = m->m_next) {
- KASSERT(m->m_flags & M_BLOCKED,
- ("%s: m %p !M_BLOCKED", __func__, m));
- m->m_flags &= ~M_BLOCKED;
+ for (; m && (m->m_flags & M_NOTREADY) == 0; m = m->m_next)
sb->sb_acc += m->m_len;
- }
sb->sb_fnrdy = m;
sbready_compress(sb, m0, m);
@@ -269,8 +264,7 @@ sballoc(struct sockbuf *sb, struct mbuf *m)
sb->sb_fnrdy = m;
else
sb->sb_acc += m->m_len;
- } else
- m->m_flags |= M_BLOCKED;
+ }
if (m->m_type != MT_DATA && m->m_type != MT_OOBDATA)
sb->sb_ctl += m->m_len;
@@ -287,29 +281,29 @@ sballoc(struct sockbuf *sb, struct mbuf *m)
void
sbfree(struct sockbuf *sb, struct mbuf *m)
{
+ struct mbuf *n;
#if 0 /* XXX: not yet: soclose() call path comes here w/o lock. */
SOCKBUF_LOCK_ASSERT(sb);
#endif
-
sb->sb_ccc -= m->m_len;
- if (!(m->m_flags & M_NOTAVAIL))
- sb->sb_acc -= m->m_len;
-
if (m == sb->sb_fnrdy) {
- struct mbuf *n;
-
KASSERT(m->m_flags & M_NOTREADY,
("%s: m %p !M_NOTREADY", __func__, m));
n = m->m_next;
while (n != NULL && !(n->m_flags & M_NOTREADY)) {
- n->m_flags &= ~M_BLOCKED;
sb->sb_acc += n->m_len;
n = n->m_next;
}
sb->sb_fnrdy = n;
+ } else {
+ /* Assert that mbuf is not behind sb_fnrdy. */
+ for (n = sb->sb_fnrdy; n != NULL; n = n->m_next)
+ KASSERT(n != m, ("%s: sb %p freeing %p behind sb_fnrdy",
+ __func__, sb, m));
+ sb->sb_acc -= m->m_len;
}
if (m->m_type != MT_DATA && m->m_type != MT_OOBDATA)
@@ -1129,13 +1123,7 @@ sbcheck(struct sockbuf *sb, const char *file, int line)
}
fnrdy = m;
}
- if (fnrdy) {
- if (!(m->m_flags & M_NOTAVAIL)) {
- printf("sb %p: fnrdy %p, m %p is avail\n",
- sb, sb->sb_fnrdy, m);
- goto fail;
- }
- } else
+ if (fnrdy == NULL)
acc += m->m_len;
ccc += m->m_len;
mbcnt += MSIZE;
@@ -1602,8 +1590,8 @@ sbcut_internal(struct sockbuf *sb, int len)
next = m->m_nextpkt;
}
if (m->m_len > len) {
- KASSERT(!(m->m_flags & M_NOTAVAIL),
- ("%s: m %p M_NOTAVAIL", __func__, m));
+ KASSERT(!(m->m_flags & M_NOTREADY),
+ ("%s: m %p M_NOTREADY", __func__, m));
m->m_len -= len;
m->m_data += len;
sb->sb_ccc -= len;
diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index 4e8c179acee9..17b456deb71f 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -3342,7 +3342,7 @@ deliver:
for (m = sb->sb_mb;
m != NULL && m->m_len <= len;
m = m->m_next) {
- KASSERT(!(m->m_flags & M_NOTAVAIL),
+ KASSERT(!(m->m_flags & M_NOTREADY),
("%s: m %p not available", __func__, m));
len -= m->m_len;
uio->uio_resid -= m->m_len;
diff --git a/sys/sys/sockbuf.h b/sys/sys/sockbuf.h
index 2fed44bc9825..b4593f38f592 100644
--- a/sys/sys/sockbuf.h
+++ b/sys/sys/sockbuf.h
@@ -210,8 +210,6 @@ typedef enum { SO_RCV, SO_SND } sb_which;
* Socket buffer private mbuf(9) flags.
*/
#define M_NOTREADY M_PROTO1 /* m_data not populated yet */
-#define M_BLOCKED M_PROTO2 /* M_NOTREADY in front of m */
-#define M_NOTAVAIL (M_NOTREADY | M_BLOCKED)
void sbappend(struct sockbuf *sb, struct mbuf *m, int flags);
void sbappend_locked(struct sockbuf *sb, struct mbuf *m, int flags);