LinuxLists.cc - [PATCH net-next v2 00/18] Remove use of list iterator after loop body

2022-04-12 20:35:15

Subject: [PATCH net-next v2 00/18] Remove use of list iterator after loop body

When the list iterator loop does not exit early the list iterator variable
contains a type-confused pointer to a 'bogus' list element computed based
on the head [1].

Often a 'found' variable is used to ensure the list iterator
variable is only accessed after the loop body if the loop did exit early
(using a break or goto).

In other cases that list iterator variable is used in
combination to access the list member which reverses the invocation of
container_of() and brings back a "safe" pointer to the head of the list.

Since, due to this code patten, there were quite a few bugs discovered [2],
Linus concluded that the rule should be to never use the list iterator
after the loop and introduce a dedicated pointer for that [3].

With the new gnu11 standard, it will now be possible to limit the scope
of the list iterator variable to the traversal loop itself by defining
the variable within the for loop.
This, however, requires to remove all uses of the list iterator after
the loop.

Based on input from Paolo Abeni [4], Vinicius Costa Gomes [5], and
Jakub Kicinski [6], I've splitted all the net-next related changes into
two patch sets, where this is part 1.

v1->v2:
- Fixed commit message for PATCH 14/18 and used dedicated variable
pointing to the position (Edward Cree)
- Removed redundant check in mv88e6xxx_port_vlan() (Vladimir Oltean)
- Refactor mv88e6xxx_port_vlan() using separate list iterator functions
(Vladimir Oltean)
- Refactor sja1105_insert_gate_entry() to use separate list iterator
functions (Vladimir Oltean)
- Allow early return in sja1105_insert_gate_entry() if
sja1105_first_entry_longer_than() didn't find any element
(Vladimir Oltean)
- Use list_add_tail() instead of list_add() in sja1105_insert_gate_entry()
(Jakub Kicinski)
- net: netcp: also use separate 'pos' variable instead of duplicating list_add()

Link: https://lwn.net/Articles/887097/ [1]
Link: https://lore.kernel.org/linux-kernel/[email protected]/ [2]
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [3]
Link: https://lore.kernel.org/linux-kernel/[email protected]/ [4]
Link: https://lore.kernel.org/linux-kernel/[email protected]/ [5]
Link: https://lore.kernel.org/linux-kernel/[email protected]/ [6]

Jakob Koschel (18):
connector: Replace usage of found with dedicated list iterator
variable
net: dsa: sja1105: remove use of iterator after list_for_each_entry()
loop
net: dsa: sja1105: reorder sja1105_first_entry_longer_than with memory
allocation
net: dsa: sja1105: use list_add_tail(pos) instead of
list_add(pos->prev)
net: dsa: mv88e6xxx: remove redundant check in mv88e6xxx_port_vlan()
net: dsa: mv88e6xxx: refactor mv88e6xxx_port_vlan()
net: dsa: Replace usage of found with dedicated list iterator variable
net: sparx5: Replace usage of found with dedicated list iterator
variable
qed: Use dedicated list iterator variable
qed: Replace usage of found with dedicated list iterator variable
qed: Remove usage of list iterator variable after the loop
net: qede: Replace usage of found with dedicated list iterator
variable
net: qede: Remove check of list iterator against head past the loop
body
sfc: Remove usage of list iterator for list_add() after the loop body
net: netcp: Remove usage of list iterator for list_add() after loop
body
ps3_gelic: Replace usage of found with dedicated list iterator
variable
ipvlan: Remove usage of list iterator variable for the loop body
team: Remove use of list iterator variable for
list_for_each_entry_from()

drivers/connector/cn_queue.c | 13 ++---
drivers/net/dsa/mv88e6xxx/chip.c | 57 ++++++++++---------
drivers/net/dsa/sja1105/sja1105_vl.c | 51 +++++++++--------
.../microchip/sparx5/sparx5_mactable.c | 25 ++++----
drivers/net/ethernet/qlogic/qed/qed_dev.c | 11 ++--
drivers/net/ethernet/qlogic/qed/qed_iwarp.c | 26 ++++-----
drivers/net/ethernet/qlogic/qed/qed_spq.c | 6 +-
.../net/ethernet/qlogic/qede/qede_filter.c | 11 ++--
drivers/net/ethernet/qlogic/qede/qede_rdma.c | 11 ++--
drivers/net/ethernet/sfc/rx_common.c | 8 ++-
drivers/net/ethernet/ti/netcp_core.c | 14 +++--
.../net/ethernet/toshiba/ps3_gelic_wireless.c | 30 +++++-----
drivers/net/ipvlan/ipvlan_main.c | 7 ++-
drivers/net/team/team.c | 20 ++++---
net/dsa/dsa.c | 11 ++--
15 files changed, 163 insertions(+), 138 deletions(-)

base-commit: 3e732ebf7316ac83e8562db7e64cc68aec390a18
--
2.25.1

2022-04-12 20:46:40

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 12/18] net: qede: Replace usage of found with dedicated list iterator variable

2022-04-12 20:49:31

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 03/18] net: dsa: sja1105: reorder sja1105_first_entry_longer_than with memory allocation

sja1105_first_entry_longer_than() does not make use of the full struct
sja1105_gate_entry *e, just of e->interval which is set from the passed
entry_time.

This means that if there is a gate conflict, we have allocated e for
nothing, just to free it later. Reorder the memory allocation and the
function call, to avoid that and simplify the error unwind path.

Signed-off-by: Jakob Koschel <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
---
drivers/net/dsa/sja1105/sja1105_vl.c | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_vl.c b/drivers/net/dsa/sja1105/sja1105_vl.c
index 369be2ac3587..e5ea8eb9ec4e 100644
--- a/drivers/net/dsa/sja1105/sja1105_vl.c
+++ b/drivers/net/dsa/sja1105/sja1105_vl.c
@@ -36,7 +36,11 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
{
struct sja1105_gate_entry *e;
struct list_head *pos;
- int rc;
+
+ pos = sja1105_first_entry_longer_than(&gating_cfg->entries,
+ entry_time, extack);
+ if (IS_ERR(pos))
+ return PTR_ERR(pos);

e = kzalloc(sizeof(*e), GFP_KERNEL);
if (!e)
@@ -45,22 +49,11 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
e->rule = rule;
e->gate_state = gate_state;
e->interval = entry_time;
-
- pos = sja1105_first_entry_longer_than(&gating_cfg->entries,
- e->interval, extack);
- if (IS_ERR(pos)) {
- rc = PTR_ERR(pos);
- goto err;
- }
-
list_add(&e->list, pos->prev);

gating_cfg->num_entries++;

return 0;
-err:
- kfree(e);
- return rc;
}

/* The gate entries contain absolute times in their e->interval field. Convert
--
2.25.1

2022-04-12 20:50:58

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 08/18] net: sparx5: Replace usage of found with dedicated list iterator variable

To move the list iterator variable into the list_for_each_entry_*()
macro in the future it should be avoided to use the list iterator
variable after the loop body.

To *never* use the list iterator variable after the loop it was
concluded to use a separate iterator variable instead of a
found boolean [1].

This removes the need to use a found variable and simply checking if
the variable was set, can determine if the break/goto was hit.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <[email protected]>
---
.../microchip/sparx5/sparx5_mactable.c | 25 +++++++++----------
1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c b/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
index a5837dbe0c7e..bb8d9ce79ac2 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
@@ -362,8 +362,7 @@ static void sparx5_mact_handle_entry(struct sparx5 *sparx5,
unsigned char mac[ETH_ALEN],
u16 vid, u32 cfg2)
{
- struct sparx5_mact_entry *mact_entry;
- bool found = false;
+ struct sparx5_mact_entry *mact_entry = NULL, *iter;
u16 port;

if (LRN_MAC_ACCESS_CFG_2_MAC_ENTRY_ADDR_TYPE_GET(cfg2) !=
@@ -378,28 +377,28 @@ static void sparx5_mact_handle_entry(struct sparx5 *sparx5,
return;

mutex_lock(&sparx5->mact_lock);
- list_for_each_entry(mact_entry, &sparx5->mact_entries, list) {
- if (mact_entry->vid == vid &&
- ether_addr_equal(mac, mact_entry->mac)) {
- found = true;
- mact_entry->flags |= MAC_ENT_ALIVE;
- if (mact_entry->port != port) {
+ list_for_each_entry(iter, &sparx5->mact_entries, list) {
+ if (iter->vid == vid &&
+ ether_addr_equal(mac, iter->mac)) {
+ iter->flags |= MAC_ENT_ALIVE;
+ if (iter->port != port) {
dev_warn(sparx5->dev, "Entry move: %d -> %d\n",
- mact_entry->port, port);
- mact_entry->port = port;
- mact_entry->flags |= MAC_ENT_MOVED;
+ iter->port, port);
+ iter->port = port;
+ iter->flags |= MAC_ENT_MOVED;
}
/* Entry handled */
+ mact_entry = iter;
break;
}
}
mutex_unlock(&sparx5->mact_lock);

- if (found && !(mact_entry->flags & MAC_ENT_MOVED))
+ if (mact_entry && !(mact_entry->flags & MAC_ENT_MOVED))
/* Present, not moved */
return;

- if (!found) {
+ if (!mact_entry) {
/* Entry not found - now add */
mact_entry = alloc_mact_entry(sparx5, mac, vid, port);
if (!mact_entry)
--
2.25.1

2022-04-12 20:58:44

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 13/18] net: qede: Remove check of list iterator against head past the loop body

When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&pos->member == head, using the iterator variable after the loop should
be avoided.

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <[email protected]>
---
drivers/net/ethernet/qlogic/qede/qede_filter.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qede/qede_filter.c b/drivers/net/ethernet/qlogic/qede/qede_filter.c
index 3010833ddde3..3d167e37e654 100644
--- a/drivers/net/ethernet/qlogic/qede/qede_filter.c
+++ b/drivers/net/ethernet/qlogic/qede/qede_filter.c
@@ -829,18 +829,21 @@ int qede_configure_vlan_filters(struct qede_dev *edev)
int qede_vlan_rx_kill_vid(struct net_device *dev, __be16 proto, u16 vid)
{
struct qede_dev *edev = netdev_priv(dev);
- struct qede_vlan *vlan;
+ struct qede_vlan *vlan = NULL;
+ struct qede_vlan *iter;
int rc = 0;

DP_VERBOSE(edev, NETIF_MSG_IFDOWN, "Removing vlan 0x%04x\n", vid);

/* Find whether entry exists */
__qede_lock(edev);
- list_for_each_entry(vlan, &edev->vlan_list, list)
- if (vlan->vid == vid)
+ list_for_each_entry(iter, &edev->vlan_list, list)
+ if (iter->vid == vid) {
+ vlan = iter;
break;
+ }

- if (list_entry_is_head(vlan, &edev->vlan_list, list)) {
+ if (!vlan) {
DP_VERBOSE(edev, (NETIF_MSG_IFUP | NETIF_MSG_IFDOWN),
"Vlan isn't configured\n");
goto out;
--
2.25.1

2022-04-12 21:13:04

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 04/18] net: dsa: sja1105: use list_add_tail(pos) instead of list_add(pos->prev)

When passed a non-head list element, list_add_tail() actually adds the
new element to its left, which is what we want. Despite the slightly
confusing name, use the dedicated function which does the same thing as
the open-coded list_add(pos->prev).

Suggested-by: Jakub Kicinski <[email protected]>
Signed-off-by: Jakob Koschel <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
---
drivers/net/dsa/sja1105/sja1105_vl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_vl.c b/drivers/net/dsa/sja1105/sja1105_vl.c
index e5ea8eb9ec4e..7fe9b18f1cbd 100644
--- a/drivers/net/dsa/sja1105/sja1105_vl.c
+++ b/drivers/net/dsa/sja1105/sja1105_vl.c
@@ -49,7 +49,7 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
e->rule = rule;
e->gate_state = gate_state;
e->interval = entry_time;
- list_add(&e->list, pos->prev);
+ list_add_tail(&e->list, pos);

gating_cfg->num_entries++;

--
2.25.1

2022-04-12 21:22:50

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 15/18] net: netcp: Remove usage of list iterator for list_add() after loop body

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer pointing to the location
where the element should be inserted [1].

Before, the code implicitly used the head when no element was found
when using &next->list. The new 'pos' variable is set to the list head
by default and overwritten if the list exits early, marking the
insertion point for list_add().

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <[email protected]>
---
drivers/net/ethernet/ti/netcp_core.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index 16507bff652a..f25104b5a31b 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c
@@ -471,6 +471,7 @@ struct netcp_hook_list {
int netcp_register_txhook(struct netcp_intf *netcp_priv, int order,
netcp_hook_rtn *hook_rtn, void *hook_data)
{
+ struct list_head *pos = &netcp_priv->txhook_list_head;
struct netcp_hook_list *entry;
struct netcp_hook_list *next;
unsigned long flags;
@@ -485,10 +486,12 @@ int netcp_register_txhook(struct netcp_intf *netcp_priv, int order,

spin_lock_irqsave(&netcp_priv->lock, flags);
list_for_each_entry(next, &netcp_priv->txhook_list_head, list) {
- if (next->order > order)
+ if (next->order > order) {
+ pos = &next->list;
break;
+ }
}
- __list_add(&entry->list, next->list.prev, &next->list);
+ list_add_tail(&entry->list, pos);
spin_unlock_irqrestore(&netcp_priv->lock, flags);

return 0;
@@ -520,6 +523,7 @@ EXPORT_SYMBOL_GPL(netcp_unregister_txhook);
int netcp_register_rxhook(struct netcp_intf *netcp_priv, int order,
netcp_hook_rtn *hook_rtn, void *hook_data)
{
+ struct list_head *pos = &netcp_priv->rxhook_list_head;
struct netcp_hook_list *entry;
struct netcp_hook_list *next;
unsigned long flags;
@@ -534,10 +538,12 @@ int netcp_register_rxhook(struct netcp_intf *netcp_priv, int order,

spin_lock_irqsave(&netcp_priv->lock, flags);
list_for_each_entry(next, &netcp_priv->rxhook_list_head, list) {
- if (next->order > order)
+ if (next->order > order) {
+ pos = &next->list;
break;
+ }
}
- __list_add(&entry->list, next->list.prev, &next->list);
+ list_add_tail(&entry->list, pos);
spin_unlock_irqrestore(&netcp_priv->lock, flags);

return 0;
--
2.25.1

2022-04-12 21:29:02

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 05/18] net: dsa: mv88e6xxx: remove redundant check in mv88e6xxx_port_vlan()

We know that "dev > dst->last_switch" in the "else" block.
In other words, that "dev - dst->last_switch" is > 0.

dsa_port_bridge_num_get(dp) can be 0, but the check
"if (bridge_num + dst->last_switch != dev) continue", rewritten as
"if (bridge_num != dev - dst->last_switch) continue", aka
"if (bridge_num != something which cannot be 0) continue",
makes it redundant to have the extra "if (!bridge_num) continue" logic,
since a bridge_num of zero would have been skipped anyway.

Signed-off-by: Jakob Koschel <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
---
drivers/net/dsa/mv88e6xxx/chip.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 64f4fdd02902..b3aa0e5bc842 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -1404,9 +1404,6 @@ static u16 mv88e6xxx_port_vlan(struct mv88e6xxx_chip *chip, int dev, int port)
list_for_each_entry(dp, &dst->ports, list) {
unsigned int bridge_num = dsa_port_bridge_num_get(dp);

- if (!bridge_num)
- continue;
-
if (bridge_num + dst->last_switch != dev)
continue;

--
2.25.1

2022-04-12 21:29:55

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 18/18] team: Remove use of list iterator variable for list_for_each_entry_from()

In preparation to limit the scope of the list iterator variable to the
list traversal loop, use a dedicated pointer to iterate through the
list [1].

Since that variable should not be used past the loop iteration, a
separate variable is used to 'remember the current location within the
loop'.

To either continue iterating from that position or skip the iteration
(if the previous iteration was complete) list_prepare_entry() is used.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <[email protected]>
---
drivers/net/team/team.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index b07dde6f0abf..688c4393f099 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -2425,17 +2425,17 @@ static int team_nl_send_options_get(struct team *team, u32 portid, u32 seq,
int flags, team_nl_send_func_t *send_func,
struct list_head *sel_opt_inst_list)
{
+ struct team_option_inst *opt_inst, *tmp = NULL;
struct nlattr *option_list;
struct nlmsghdr *nlh;
void *hdr;
- struct team_option_inst *opt_inst;
int err;
struct sk_buff *skb = NULL;
bool incomplete;
int i;

- opt_inst = list_first_entry(sel_opt_inst_list,
- struct team_option_inst, tmp_list);
+ tmp = list_first_entry(sel_opt_inst_list,
+ struct team_option_inst, tmp_list);

start_again:
err = __send_and_alloc_skb(&skb, team, portid, send_func);
@@ -2456,7 +2456,9 @@ static int team_nl_send_options_get(struct team *team, u32 portid, u32 seq,
goto nla_put_failure;

i = 0;
+ opt_inst = list_prepare_entry(tmp, sel_opt_inst_list, tmp_list);
incomplete = false;
+ tmp = NULL;
list_for_each_entry_from(opt_inst, sel_opt_inst_list, tmp_list) {
err = team_nl_fill_one_option_get(skb, team, opt_inst);
if (err) {
@@ -2464,6 +2466,7 @@ static int team_nl_send_options_get(struct team *team, u32 portid, u32 seq,
if (!i)
goto errout;
incomplete = true;
+ tmp = opt_inst;
break;
}
goto errout;
@@ -2707,14 +2710,14 @@ static int team_nl_send_port_list_get(struct team *team, u32 portid, u32 seq,
struct nlattr *port_list;
struct nlmsghdr *nlh;
void *hdr;
- struct team_port *port;
+ struct team_port *port, *tmp = NULL;
int err;
struct sk_buff *skb = NULL;
bool incomplete;
int i;

- port = list_first_entry_or_null(&team->port_list,
- struct team_port, list);
+ tmp = list_first_entry_or_null(&team->port_list,
+ struct team_port, list);

start_again:
err = __send_and_alloc_skb(&skb, team, portid, send_func);
@@ -2744,7 +2747,9 @@ static int team_nl_send_port_list_get(struct team *team, u32 portid, u32 seq,
err = team_nl_fill_one_port_get(skb, one_port);
if (err)
goto errout;
- } else if (port) {
+ } else {
+ port = list_prepare_entry(tmp, &team->port_list, list);
+ tmp = NULL;
list_for_each_entry_from(port, &team->port_list, list) {
err = team_nl_fill_one_port_get(skb, port);
if (err) {
@@ -2752,6 +2757,7 @@ static int team_nl_send_port_list_get(struct team *team, u32 portid, u32 seq,
if (!i)
goto errout;
incomplete = true;
+ tmp = port;
break;
}
goto errout;
--
2.25.1

2022-04-12 21:31:57

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 17/18] ipvlan: Remove usage of list iterator variable for the loop body

2022-04-12 21:52:47

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 09/18] qed: Use dedicated list iterator variable

2022-04-12 21:58:10

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 06/18] net: dsa: mv88e6xxx: refactor mv88e6xxx_port_vlan()

To avoid bugs and speculative execution exploits due to type-confused
pointers at the end of a list_for_each_entry() loop, one measure is to
restrict code to not use the iterator variable outside the loop block.

In the case of mv88e6xxx_port_vlan(), this isn't a problem, as we never
let the loops exit through "natural causes" anyway, by using a "found"
variable and then using the last "dp" iterator prior to the break, which
is a safe thing to do.

Nonetheless, with the expected new syntax, this pattern will no longer
be possible.

Profit off of the occasion and break the two port finding methods into
smaller sub-functions. Somehow, returning a copy of the iterator pointer
is still accepted.

This change makes it redundant to have a "bool found", since the "dp"
from mv88e6xxx_port_vlan() now holds NULL if we haven't found what we
were looking for.

Signed-off-by: Jakob Koschel <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
---
drivers/net/dsa/mv88e6xxx/chip.c | 54 ++++++++++++++++++--------------
1 file changed, 31 insertions(+), 23 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index b3aa0e5bc842..1f35e89053e6 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -1378,42 +1378,50 @@ static int mv88e6xxx_set_mac_eee(struct dsa_switch *ds, int port,
return 0;
}

+static struct dsa_port *mv88e6xxx_find_port(struct dsa_switch_tree *dst,
+ int sw_index, int port)
+{
+ struct dsa_port *dp;
+
+ list_for_each_entry(dp, &dst->ports, list)
+ if (dp->ds->index == sw_index && dp->index == port)
+ return dp;
+
+ return NULL;
+}
+
+static struct dsa_port *
+mv88e6xxx_find_port_by_bridge_num(struct dsa_switch_tree *dst,
+ unsigned int bridge_num)
+{
+ struct dsa_port *dp;
+
+ list_for_each_entry(dp, &dst->ports, list)
+ if (dsa_port_bridge_num_get(dp) == bridge_num)
+ return dp;
+
+ return NULL;
+}
+
/* Mask of the local ports allowed to receive frames from a given fabric port */
static u16 mv88e6xxx_port_vlan(struct mv88e6xxx_chip *chip, int dev, int port)
{
struct dsa_switch *ds = chip->ds;
struct dsa_switch_tree *dst = ds->dst;
struct dsa_port *dp, *other_dp;
- bool found = false;
u16 pvlan;

- /* dev is a physical switch */
if (dev <= dst->last_switch) {
- list_for_each_entry(dp, &dst->ports, list) {
- if (dp->ds->index == dev && dp->index == port) {
- /* dp might be a DSA link or a user port, so it
- * might or might not have a bridge.
- * Use the "found" variable for both cases.
- */
- found = true;
- break;
- }
- }
- /* dev is a virtual bridge */
+ /* dev is a physical switch */
+ dp = mv88e6xxx_find_port(dst, dev, port);
} else {
- list_for_each_entry(dp, &dst->ports, list) {
- unsigned int bridge_num = dsa_port_bridge_num_get(dp);
-
- if (bridge_num + dst->last_switch != dev)
- continue;
-
- found = true;
- break;
- }
+ /* dev is a virtual bridge */
+ dp = mv88e6xxx_find_port_by_bridge_num(dst,
+ dev - dst->last_switch);
}

/* Prevent frames from unknown switch or virtual bridge */
- if (!found)
+ if (!dp)
return 0;

/* Frames from DSA links and CPU ports can egress any local port */
--
2.25.1

2022-04-12 22:17:04

by Russell King (Oracle)

[permalink] [raw]

Subject: Re: [PATCH net-next v2 05/18] net: dsa: mv88e6xxx: remove redundant check in mv88e6xxx_port_vlan()

On Tue, Apr 12, 2022 at 12:58:17PM +0200, Jakob Koschel wrote:
> We know that "dev > dst->last_switch" in the "else" block.
> In other words, that "dev - dst->last_switch" is > 0.
>
> dsa_port_bridge_num_get(dp) can be 0, but the check
> "if (bridge_num + dst->last_switch != dev) continue", rewritten as
> "if (bridge_num != dev - dst->last_switch) continue", aka
> "if (bridge_num != something which cannot be 0) continue",
> makes it redundant to have the extra "if (!bridge_num) continue" logic,
> since a bridge_num of zero would have been skipped anyway.
>
> Signed-off-by: Jakob Koschel <[email protected]>
> Signed-off-by: Vladimir Oltean <[email protected]>

Isn't this Vladimir's patch?

If so, it should be commited as Vladimir as the author, and Vladimir's
sign-off should appear before yours. When sending out such patches,
there should be a From: line for Vladimir as the first line in the body
of the patch email.

The same goes for the next mv88e6xxx patch in this series - I think
both of these are the patches Vladimir sent in his email:

https://lore.kernel.org/r/20220408123101.p33jpynhqo67hebe@skbuf

Thanks.

--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

2022-04-12 22:20:11

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 10/18] qed: Replace usage of found with dedicated list iterator variable

To move the list iterator variable into the list_for_each_entry_*()
macro in the future it should be avoided to use the list iterator
variable after the loop body.

To *never* use the list iterator variable after the loop it was
concluded to use a separate iterator variable instead of a
found boolean [1].

This removes the need to use a found variable and simply checking if
the variable was set, can determine if the break/goto was hit.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <[email protected]>
---
drivers/net/ethernet/qlogic/qed/qed_iwarp.c | 26 ++++++++++-----------
1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_iwarp.c b/drivers/net/ethernet/qlogic/qed/qed_iwarp.c
index 1d1d4caad680..198c9321bf51 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_iwarp.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_iwarp.c
@@ -1630,38 +1630,36 @@ static struct qed_iwarp_listener *
qed_iwarp_get_listener(struct qed_hwfn *p_hwfn,
struct qed_iwarp_cm_info *cm_info)
{
- struct qed_iwarp_listener *listener = NULL;
+ struct qed_iwarp_listener *listener = NULL, *iter;
static const u32 ip_zero[4] = { 0, 0, 0, 0 };
- bool found = false;

- list_for_each_entry(listener,
+ list_for_each_entry(iter,
&p_hwfn->p_rdma_info->iwarp.listen_list,
list_entry) {
- if (listener->port == cm_info->local_port) {
- if (!memcmp(listener->ip_addr,
+ if (iter->port == cm_info->local_port) {
+ if (!memcmp(iter->ip_addr,
ip_zero, sizeof(ip_zero))) {
- found = true;
+ listener = iter;
break;
}

- if (!memcmp(listener->ip_addr,
+ if (!memcmp(iter->ip_addr,
cm_info->local_ip,
sizeof(cm_info->local_ip)) &&
- (listener->vlan == cm_info->vlan)) {
- found = true;
+ iter->vlan == cm_info->vlan) {
+ listener = iter;
break;
}
}
}

- if (found) {
+ if (listener)
DP_VERBOSE(p_hwfn, QED_MSG_RDMA, "listener found = %p\n",
listener);
- return listener;
- }
+ else
+ DP_VERBOSE(p_hwfn, QED_MSG_RDMA, "listener not found\n");

- DP_VERBOSE(p_hwfn, QED_MSG_RDMA, "listener not found\n");
- return NULL;
+ return listener;
}

static int
--
2.25.1

2022-04-13 00:11:16

by Jakob Koschel

[permalink] [raw]

Subject: [PATCH net-next v2 02/18] net: dsa: sja1105: remove use of iterator after list_for_each_entry() loop

The link below explains that there is a desire to syntactically change
list_for_each_entry() and list_for_each() such that it becomes
impossible to use the iterator variable outside the scope of the loop.

Although sja1105_insert_gate_entry() makes legitimate use of the
iterator pointer when it breaks out, the pattern it uses may become
illegal, so it needs to change.

It is deemed acceptable to use a copy of the loop iterator, and
sja1105_insert_gate_entry() only needs to know the list_head element
before which the list insertion should be made. So let's profit from the
occasion and refactor the list iteration to a dedicated function.

An additional benefit is given by the fact that with the helper function
in place, we no longer need to special-case the empty list, since it is
equivalent to not having found any gating entry larger than the
specified interval in the list. We just need to insert at the tail of
that list (list_add vs list_add_tail on an empty list does the same
thing).

Link: https://patchwork.kernel.org/project/netdevbpf/patch/[email protected]/#24810127
Signed-off-by: Jakob Koschel <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
---
drivers/net/dsa/sja1105/sja1105_vl.c | 46 ++++++++++++++++++----------
1 file changed, 29 insertions(+), 17 deletions(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_vl.c b/drivers/net/dsa/sja1105/sja1105_vl.c
index b7e95d60a6e4..369be2ac3587 100644
--- a/drivers/net/dsa/sja1105/sja1105_vl.c
+++ b/drivers/net/dsa/sja1105/sja1105_vl.c
@@ -7,6 +7,27 @@

#define SJA1105_SIZE_VL_STATUS 8

+static struct list_head *
+sja1105_first_entry_longer_than(struct list_head *entries,
+ s64 interval,
+ struct netlink_ext_ack *extack)
+{
+ struct sja1105_gate_entry *p;
+
+ list_for_each_entry(p, entries, list) {
+ if (p->interval == interval) {
+ NL_SET_ERR_MSG_MOD(extack, "Gate conflict");
+ return ERR_PTR(-EBUSY);
+ }
+
+ if (interval < p->interval)
+ return &p->list;
+ }
+
+ /* Empty list, or specified interval is largest within the list */
+ return entries;
+}
+
/* Insert into the global gate list, sorted by gate action time. */
static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
struct sja1105_rule *rule,
@@ -14,6 +35,7 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
struct netlink_ext_ack *extack)
{
struct sja1105_gate_entry *e;
+ struct list_head *pos;
int rc;

e = kzalloc(sizeof(*e), GFP_KERNEL);
@@ -24,25 +46,15 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
e->gate_state = gate_state;
e->interval = entry_time;

- if (list_empty(&gating_cfg->entries)) {
- list_add(&e->list, &gating_cfg->entries);
- } else {
- struct sja1105_gate_entry *p;
-
- list_for_each_entry(p, &gating_cfg->entries, list) {
- if (p->interval == e->interval) {
- NL_SET_ERR_MSG_MOD(extack,
- "Gate conflict");
- rc = -EBUSY;
- goto err;
- }
-
- if (e->interval < p->interval)
- break;
- }
- list_add(&e->list, p->list.prev);
+ pos = sja1105_first_entry_longer_than(&gating_cfg->entries,
+ e->interval, extack);
+ if (IS_ERR(pos)) {
+ rc = PTR_ERR(pos);
+ goto err;
}

+ list_add(&e->list, pos->prev);
+
gating_cfg->num_entries++;

return 0;
--
2.25.1