Revert "Scm: Remove unnecessary pid & credential references in Unix socket's send and receive path"

This reverts commit 0856a304091b33a8e8f9f9c98e776f425af2b625. As requested by Eric Dumazet, it has various ref-counting problems and has introduced regressions. Eric will add a more suitable version of this performance fix. Signed-off-by: David S. Miller <davem@davemloft.net>

Revert "Scm: Remove unnecessary pid & credential references in Unix socket's send and receive path"
This reverts commit 0856a304091b33a8e8f9f9c98e776f425af2b625. As requested by Eric Dumazet, it has various ref-counting problems and has introduced regressions. Eric will add a more suitable version of this performance fix. Signed-off-by: David S. Miller <davem@davemloft.net>
David S. Miller
1 parent 473e64ee46
Showing 2 changed files with 19 additions and 48 deletions Side-by-side Diff
include/net/scm.h
net/unix/af_unix.c
@@ -53,14 +53,6 @@
 	cred_to_ucred(pid, cred, &scm->creds);
 }
  
-static __inline__ void scm_set_cred_noref(struct scm_cookie *scm,
-				    struct pid *pid, const struct cred *cred)
-{
-	scm->pid  = pid;
-	scm->cred = cred;
-	cred_to_ucred(pid, cred, &scm->creds);
-}
-
 static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
 {
 	put_pid(scm->pid);
@@ -78,15 +70,6 @@
 		__scm_destroy(scm);
 }
  
-static __inline__ void scm_release(struct scm_cookie *scm)
-{
-	/* keep ref on pid and cred */
-	scm->pid = NULL;
-	scm->cred = NULL;
-	if (scm->fp)
-		__scm_destroy(scm);
-}
-
 static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
 			       struct scm_cookie *scm)
 {
  
@@ -125,13 +108,14 @@
 	if (!msg->msg_control) {
 		if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
 			msg->msg_flags |= MSG_CTRUNC;
-		if (scm && scm->fp)
-			__scm_destroy(scm);
+		scm_destroy(scm);
 		return;
 	}
  
 	if (test_bit(SOCK_PASSCRED, &sock->flags))
 		put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(scm->creds), &scm->creds);
+
+	scm_destroy_cred(scm);
  
 	scm_passec(sock, msg, scm);
  
@@ -1378,17 +1378,11 @@
 	return max_level;
 }
  
-static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb,
-			   bool send_fds, bool ref)
+static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
 {
 	int err = 0;
-	if (ref) {
-		UNIXCB(skb).pid  = get_pid(scm->pid);
-		UNIXCB(skb).cred = get_cred(scm->cred);
-	} else {
-		UNIXCB(skb).pid  = scm->pid;
-		UNIXCB(skb).cred = scm->cred;
-	}
+	UNIXCB(skb).pid  = get_pid(scm->pid);
+	UNIXCB(skb).cred = get_cred(scm->cred);
 	UNIXCB(skb).fp = NULL;
 	if (scm->fp && send_fds)
 		err = unix_attach_fds(scm, skb);
@@ -1413,7 +1407,7 @@
 	int namelen = 0; /* fake GCC */
 	int err;
 	unsigned hash;
-	struct sk_buff *skb = NULL;
+	struct sk_buff *skb;
 	long timeo;
 	struct scm_cookie tmp_scm;
 	int max_level;
@@ -1454,7 +1448,7 @@
 	if (skb == NULL)
 		goto out;
  
-	err = unix_scm_to_skb(siocb->scm, skb, true, false);
+	err = unix_scm_to_skb(siocb->scm, skb, true);
 	if (err < 0)
 		goto out_free;
 	max_level = err + 1;
@@ -1550,7 +1544,7 @@
 	unix_state_unlock(other);
 	other->sk_data_ready(other, len);
 	sock_put(other);
-	scm_release(siocb->scm);
+	scm_destroy(siocb->scm);
 	return len;
  
 out_unlock:
@@ -1560,8 +1554,7 @@
 out:
 	if (other)
 		sock_put(other);
-	if (skb == NULL)
-		scm_destroy(siocb->scm);
+	scm_destroy(siocb->scm);
 	return err;
 }
  
@@ -1573,7 +1566,7 @@
 	struct sock *sk = sock->sk;
 	struct sock *other = NULL;
 	int err, size;
-	struct sk_buff *skb = NULL;
+	struct sk_buff *skb;
 	int sent = 0;
 	struct scm_cookie tmp_scm;
 	bool fds_sent = false;
  
@@ -1638,11 +1631,11 @@
 		size = min_t(int, size, skb_tailroom(skb));
  
  
-		/* Only send the fds and no ref to pid in the first buffer */
-		err = unix_scm_to_skb(siocb->scm, skb, !fds_sent, fds_sent);
+		/* Only send the fds in the first buffer */
+		err = unix_scm_to_skb(siocb->scm, skb, !fds_sent);
 		if (err < 0) {
 			kfree_skb(skb);
-			goto out;
+			goto out_err;
 		}
 		max_level = err + 1;
 		fds_sent = true;
@@ -1650,7 +1643,7 @@
 		err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
 		if (err) {
 			kfree_skb(skb);
-			goto out;
+			goto out_err;
 		}
  
 		unix_state_lock(other);
@@ -1667,10 +1660,7 @@
 		sent += size;
 	}
  
-	if (skb)
-		scm_release(siocb->scm);
-	else
-		scm_destroy(siocb->scm);
+	scm_destroy(siocb->scm);
 	siocb->scm = NULL;
  
 	return sent;
@@ -1683,9 +1673,7 @@
 		send_sig(SIGPIPE, current, 0);
 	err = -EPIPE;
 out_err:
-	if (skb == NULL)
-		scm_destroy(siocb->scm);
-out:
+	scm_destroy(siocb->scm);
 	siocb->scm = NULL;
 	return sent ? : err;
 }
@@ -1789,7 +1777,7 @@
 		siocb->scm = &tmp_scm;
 		memset(&tmp_scm, 0, sizeof(tmp_scm));
 	}
-	scm_set_cred_noref(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
+	scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
 	unix_set_secdata(siocb->scm, skb);
  
 	if (!(flags & MSG_PEEK)) {
@@ -1951,8 +1939,7 @@
 			}
 		} else {
 			/* Copy credentials */
-			scm_set_cred_noref(siocb->scm, UNIXCB(skb).pid,
-					   UNIXCB(skb).cred);
+			scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
 			check_creds = 1;
 		}
...	...	@@ -53,14 +53,6 @@
53	53	cred_to_ucred(pid, cred, &scm->creds);
54	54	}
55	55
56		-static __inline__ void scm_set_cred_noref(struct scm_cookie *scm,
57		- struct pid pid, const struct cred cred)
58		-{
59		- scm->pid = pid;
60		- scm->cred = cred;
61		- cred_to_ucred(pid, cred, &scm->creds);
62		-}
63		-
64	56	static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
65	57	{
66	58	put_pid(scm->pid);
...	...	@@ -78,15 +70,6 @@
78	70	__scm_destroy(scm);
79	71	}
80	72
81		-static __inline__ void scm_release(struct scm_cookie *scm)
82		-{
83		- /* keep ref on pid and cred */
84		- scm->pid = NULL;
85		- scm->cred = NULL;
86		- if (scm->fp)
87		- __scm_destroy(scm);
88		-}
89		-
90	73	static __inline__ int scm_send(struct socket sock, struct msghdr msg,
91	74	struct scm_cookie *scm)
92	75	{
93	76
...	...	@@ -125,13 +108,14 @@
125	108	if (!msg->msg_control) {
126	109	if (test_bit(SOCK_PASSCRED, &sock->flags) \|\| scm->fp)
127	110	msg->msg_flags \|= MSG_CTRUNC;
128		- if (scm && scm->fp)
129		- __scm_destroy(scm);
	111	+ scm_destroy(scm);
130	112	return;
131	113	}
132	114
133	115	if (test_bit(SOCK_PASSCRED, &sock->flags))
134	116	put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(scm->creds), &scm->creds);
	117	+
	118	+ scm_destroy_cred(scm);
135	119
136	120	scm_passec(sock, msg, scm);
137	121
...	...	@@ -1378,17 +1378,11 @@
1378	1378	return max_level;
1379	1379	}
1380	1380
1381		-static int unix_scm_to_skb(struct scm_cookie scm, struct sk_buff skb,
1382		- bool send_fds, bool ref)
	1381	+static int unix_scm_to_skb(struct scm_cookie scm, struct sk_buff skb, bool send_fds)
1383	1382	{
1384	1383	int err = 0;
1385		- if (ref) {
1386		- UNIXCB(skb).pid = get_pid(scm->pid);
1387		- UNIXCB(skb).cred = get_cred(scm->cred);
1388		- } else {
1389		- UNIXCB(skb).pid = scm->pid;
1390		- UNIXCB(skb).cred = scm->cred;
1391		- }
	1384	+ UNIXCB(skb).pid = get_pid(scm->pid);
	1385	+ UNIXCB(skb).cred = get_cred(scm->cred);
1392	1386	UNIXCB(skb).fp = NULL;
1393	1387	if (scm->fp && send_fds)
1394	1388	err = unix_attach_fds(scm, skb);
...	...	@@ -1413,7 +1407,7 @@
1413	1407	int namelen = 0; /* fake GCC */
1414	1408	int err;
1415	1409	unsigned hash;
1416		- struct sk_buff *skb = NULL;
	1410	+ struct sk_buff *skb;
1417	1411	long timeo;
1418	1412	struct scm_cookie tmp_scm;
1419	1413	int max_level;
...	...	@@ -1454,7 +1448,7 @@
1454	1448	if (skb == NULL)
1455	1449	goto out;
1456	1450
1457		- err = unix_scm_to_skb(siocb->scm, skb, true, false);
	1451	+ err = unix_scm_to_skb(siocb->scm, skb, true);
1458	1452	if (err < 0)
1459	1453	goto out_free;
1460	1454	max_level = err + 1;
...	...	@@ -1550,7 +1544,7 @@
1550	1544	unix_state_unlock(other);
1551	1545	other->sk_data_ready(other, len);
1552	1546	sock_put(other);
1553		- scm_release(siocb->scm);
	1547	+ scm_destroy(siocb->scm);
1554	1548	return len;
1555	1549
1556	1550	out_unlock:
...	...	@@ -1560,8 +1554,7 @@
1560	1554	out:
1561	1555	if (other)
1562	1556	sock_put(other);
1563		- if (skb == NULL)
1564		- scm_destroy(siocb->scm);
	1557	+ scm_destroy(siocb->scm);
1565	1558	return err;
1566	1559	}
1567	1560
...	...	@@ -1573,7 +1566,7 @@
1573	1566	struct sock *sk = sock->sk;
1574	1567	struct sock *other = NULL;
1575	1568	int err, size;
1576		- struct sk_buff *skb = NULL;
	1569	+ struct sk_buff *skb;
1577	1570	int sent = 0;
1578	1571	struct scm_cookie tmp_scm;
1579	1572	bool fds_sent = false;
1580	1573
...	...	@@ -1638,11 +1631,11 @@
1638	1631	size = min_t(int, size, skb_tailroom(skb));
1639	1632
1640	1633
1641		- /* Only send the fds and no ref to pid in the first buffer */
1642		- err = unix_scm_to_skb(siocb->scm, skb, !fds_sent, fds_sent);
	1634	+ /* Only send the fds in the first buffer */
	1635	+ err = unix_scm_to_skb(siocb->scm, skb, !fds_sent);
1643	1636	if (err < 0) {
1644	1637	kfree_skb(skb);
1645		- goto out;
	1638	+ goto out_err;
1646	1639	}
1647	1640	max_level = err + 1;
1648	1641	fds_sent = true;
...	...	@@ -1650,7 +1643,7 @@
1650	1643	err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
1651	1644	if (err) {
1652	1645	kfree_skb(skb);
1653		- goto out;
	1646	+ goto out_err;
1654	1647	}
1655	1648
1656	1649	unix_state_lock(other);
...	...	@@ -1667,10 +1660,7 @@
1667	1660	sent += size;
1668	1661	}
1669	1662
1670		- if (skb)
1671		- scm_release(siocb->scm);
1672		- else
1673		- scm_destroy(siocb->scm);
	1663	+ scm_destroy(siocb->scm);
1674	1664	siocb->scm = NULL;
1675	1665
1676	1666	return sent;
...	...	@@ -1683,9 +1673,7 @@
1683	1673	send_sig(SIGPIPE, current, 0);
1684	1674	err = -EPIPE;
1685	1675	out_err:
1686		- if (skb == NULL)
1687		- scm_destroy(siocb->scm);
1688		-out:
	1676	+ scm_destroy(siocb->scm);
1689	1677	siocb->scm = NULL;
1690	1678	return sent ? : err;
1691	1679	}
...	...	@@ -1789,7 +1777,7 @@
1789	1777	siocb->scm = &tmp_scm;
1790	1778	memset(&tmp_scm, 0, sizeof(tmp_scm));
1791	1779	}
1792		- scm_set_cred_noref(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
	1780	+ scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
1793	1781	unix_set_secdata(siocb->scm, skb);
1794	1782
1795	1783	if (!(flags & MSG_PEEK)) {
...	...	@@ -1951,8 +1939,7 @@
1951	1939	}
1952	1940	} else {
1953	1941	/* Copy credentials */
1954		- scm_set_cred_noref(siocb->scm, UNIXCB(skb).pid,
1955		- UNIXCB(skb).cred);
	1942	+ scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
1956	1943	check_creds = 1;
1957	1944	}
1958	1945