intf->cmd_rcvrs is traversed with list_for_each_entry_rcu
outside an RCU read-side critical section but under the
protection of intf->cmd_rcvrs_mutex.
ipmi_interfaces is traversed using list_for_each_entry_rcu
outside an RCU read-side critical section but under the protection
of ipmi_interfaces_mutex.
Hence, add the corresponding lockdep expression to the list traversal
primitive to silence false-positive lockdep warnings, and
harden RCU lists.
Add macro for the corresponding lockdep expression to make the code
clean and concise.
Signed-off-by: Amol Grover <[email protected]>
---
v3:
- Remove rcu_read_lock_held() from lockdep expression since it is
implicitly checked.
- Remove unintended macro usage.
v2:
- Fix sparse error
CHECK: Alignment should match open parenthesis
drivers/char/ipmi/ipmi_msghandler.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index cad9563f8f48..64ba16dcb681 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -618,6 +618,8 @@ static DEFINE_MUTEX(ipmidriver_mutex);
static LIST_HEAD(ipmi_interfaces);
static DEFINE_MUTEX(ipmi_interfaces_mutex);
+#define ipmi_interfaces_mutex_held() \
+ lockdep_is_held(&ipmi_interfaces_mutex)
static struct srcu_struct ipmi_interfaces_srcu;
/*
@@ -1321,7 +1323,8 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
* synchronize_srcu()) then free everything in that list.
*/
mutex_lock(&intf->cmd_rcvrs_mutex);
- list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
+ list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
+ lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
if (rcvr->user == user) {
list_del_rcu(&rcvr->link);
rcvr->next = rcvrs;
@@ -1599,7 +1602,8 @@ static struct cmd_rcvr *find_cmd_rcvr(struct ipmi_smi *intf,
{
struct cmd_rcvr *rcvr;
- list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
+ list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
+ lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
&& (rcvr->chans & (1 << chan)))
return rcvr;
@@ -1614,7 +1618,8 @@ static int is_cmd_rcvr_exclusive(struct ipmi_smi *intf,
{
struct cmd_rcvr *rcvr;
- list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
+ list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
+ lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
&& (rcvr->chans & chans))
return 0;
@@ -3450,7 +3455,8 @@ int ipmi_add_smi(struct module *owner,
/* Look for a hole in the numbers. */
i = 0;
link = &ipmi_interfaces;
- list_for_each_entry_rcu(tintf, &ipmi_interfaces, link) {
+ list_for_each_entry_rcu(tintf, &ipmi_interfaces, link,
+ ipmi_interfaces_mutex_held()) {
if (tintf->intf_num != i) {
link = &tintf->link;
break;
--
2.24.1
On Fri, Jan 17, 2020 at 06:55:22PM +0530, Amol Grover wrote:
> intf->cmd_rcvrs is traversed with list_for_each_entry_rcu
> outside an RCU read-side critical section but under the
> protection of intf->cmd_rcvrs_mutex.
>
> ipmi_interfaces is traversed using list_for_each_entry_rcu
> outside an RCU read-side critical section but under the protection
> of ipmi_interfaces_mutex.
>
> Hence, add the corresponding lockdep expression to the list traversal
> primitive to silence false-positive lockdep warnings, and
> harden RCU lists.
>
> Add macro for the corresponding lockdep expression to make the code
> clean and concise.
>
> Signed-off-by: Amol Grover <[email protected]>
After reading everything, I think this is correct, but I would like
Paul's stamp of approval on this.
Thanks,
-corey
> ---
> v3:
> - Remove rcu_read_lock_held() from lockdep expression since it is
> implicitly checked.
> - Remove unintended macro usage.
>
> v2:
> - Fix sparse error
> CHECK: Alignment should match open parenthesis
>
> drivers/char/ipmi/ipmi_msghandler.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> index cad9563f8f48..64ba16dcb681 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -618,6 +618,8 @@ static DEFINE_MUTEX(ipmidriver_mutex);
>
> static LIST_HEAD(ipmi_interfaces);
> static DEFINE_MUTEX(ipmi_interfaces_mutex);
> +#define ipmi_interfaces_mutex_held() \
> + lockdep_is_held(&ipmi_interfaces_mutex)
> static struct srcu_struct ipmi_interfaces_srcu;
>
> /*
> @@ -1321,7 +1323,8 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
> * synchronize_srcu()) then free everything in that list.
> */
> mutex_lock(&intf->cmd_rcvrs_mutex);
> - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> if (rcvr->user == user) {
> list_del_rcu(&rcvr->link);
> rcvr->next = rcvrs;
> @@ -1599,7 +1602,8 @@ static struct cmd_rcvr *find_cmd_rcvr(struct ipmi_smi *intf,
> {
> struct cmd_rcvr *rcvr;
>
> - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
> && (rcvr->chans & (1 << chan)))
> return rcvr;
> @@ -1614,7 +1618,8 @@ static int is_cmd_rcvr_exclusive(struct ipmi_smi *intf,
> {
> struct cmd_rcvr *rcvr;
>
> - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
> && (rcvr->chans & chans))
> return 0;
> @@ -3450,7 +3455,8 @@ int ipmi_add_smi(struct module *owner,
> /* Look for a hole in the numbers. */
> i = 0;
> link = &ipmi_interfaces;
> - list_for_each_entry_rcu(tintf, &ipmi_interfaces, link) {
> + list_for_each_entry_rcu(tintf, &ipmi_interfaces, link,
> + ipmi_interfaces_mutex_held()) {
> if (tintf->intf_num != i) {
> link = &tintf->link;
> break;
> --
> 2.24.1
>
On Wed, Feb 12, 2020 at 07:45:52AM -0600, Corey Minyard wrote:
> On Fri, Jan 17, 2020 at 06:55:22PM +0530, Amol Grover wrote:
> > intf->cmd_rcvrs is traversed with list_for_each_entry_rcu
> > outside an RCU read-side critical section but under the
> > protection of intf->cmd_rcvrs_mutex.
> >
> > ipmi_interfaces is traversed using list_for_each_entry_rcu
> > outside an RCU read-side critical section but under the protection
> > of ipmi_interfaces_mutex.
> >
> > Hence, add the corresponding lockdep expression to the list traversal
> > primitive to silence false-positive lockdep warnings, and
> > harden RCU lists.
> >
> > Add macro for the corresponding lockdep expression to make the code
> > clean and concise.
> >
> > Signed-off-by: Amol Grover <[email protected]>
>
> After reading everything, I think this is correct, but I would like
> Paul's stamp of approval on this.
Acked-by: Paul E. McKenney <[email protected]>
But note that I did not trace the locking in the case of ipmi_add_smi().
I did the others, so lockdep can do the last one. ;-)
Thanx, Paul
> Thanks,
>
> -corey
>
> > ---
> > v3:
> > - Remove rcu_read_lock_held() from lockdep expression since it is
> > implicitly checked.
> > - Remove unintended macro usage.
> >
> > v2:
> > - Fix sparse error
> > CHECK: Alignment should match open parenthesis
> >
> > drivers/char/ipmi/ipmi_msghandler.c | 14 ++++++++++----
> > 1 file changed, 10 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> > index cad9563f8f48..64ba16dcb681 100644
> > --- a/drivers/char/ipmi/ipmi_msghandler.c
> > +++ b/drivers/char/ipmi/ipmi_msghandler.c
> > @@ -618,6 +618,8 @@ static DEFINE_MUTEX(ipmidriver_mutex);
> >
> > static LIST_HEAD(ipmi_interfaces);
> > static DEFINE_MUTEX(ipmi_interfaces_mutex);
> > +#define ipmi_interfaces_mutex_held() \
> > + lockdep_is_held(&ipmi_interfaces_mutex)
> > static struct srcu_struct ipmi_interfaces_srcu;
> >
> > /*
> > @@ -1321,7 +1323,8 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
> > * synchronize_srcu()) then free everything in that list.
> > */
> > mutex_lock(&intf->cmd_rcvrs_mutex);
> > - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> > + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> > + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> > if (rcvr->user == user) {
> > list_del_rcu(&rcvr->link);
> > rcvr->next = rcvrs;
> > @@ -1599,7 +1602,8 @@ static struct cmd_rcvr *find_cmd_rcvr(struct ipmi_smi *intf,
> > {
> > struct cmd_rcvr *rcvr;
> >
> > - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> > + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> > + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> > if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
> > && (rcvr->chans & (1 << chan)))
> > return rcvr;
> > @@ -1614,7 +1618,8 @@ static int is_cmd_rcvr_exclusive(struct ipmi_smi *intf,
> > {
> > struct cmd_rcvr *rcvr;
> >
> > - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> > + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> > + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> > if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
> > && (rcvr->chans & chans))
> > return 0;
> > @@ -3450,7 +3455,8 @@ int ipmi_add_smi(struct module *owner,
> > /* Look for a hole in the numbers. */
> > i = 0;
> > link = &ipmi_interfaces;
> > - list_for_each_entry_rcu(tintf, &ipmi_interfaces, link) {
> > + list_for_each_entry_rcu(tintf, &ipmi_interfaces, link,
> > + ipmi_interfaces_mutex_held()) {
> > if (tintf->intf_num != i) {
> > link = &tintf->link;
> > break;
> > --
> > 2.24.1
> >
On Wed, Feb 12, 2020 at 01:49:56PM -0800, Paul E. McKenney wrote:
> On Wed, Feb 12, 2020 at 07:45:52AM -0600, Corey Minyard wrote:
> > On Fri, Jan 17, 2020 at 06:55:22PM +0530, Amol Grover wrote:
> > > intf->cmd_rcvrs is traversed with list_for_each_entry_rcu
> > > outside an RCU read-side critical section but under the
> > > protection of intf->cmd_rcvrs_mutex.
> > >
> > > ipmi_interfaces is traversed using list_for_each_entry_rcu
> > > outside an RCU read-side critical section but under the protection
> > > of ipmi_interfaces_mutex.
> > >
> > > Hence, add the corresponding lockdep expression to the list traversal
> > > primitive to silence false-positive lockdep warnings, and
> > > harden RCU lists.
> > >
> > > Add macro for the corresponding lockdep expression to make the code
> > > clean and concise.
> > >
> > > Signed-off-by: Amol Grover <[email protected]>
> >
> > After reading everything, I think this is correct, but I would like
> > Paul's stamp of approval on this.
>
> Acked-by: Paul E. McKenney <[email protected]>
>
> But note that I did not trace the locking in the case of ipmi_add_smi().
> I did the others, so lockdep can do the last one. ;-)
Thanks, it's in my queue for 5.7.
-corey
>
> Thanx, Paul
>
> > Thanks,
> >
> > -corey
> >
> > > ---
> > > v3:
> > > - Remove rcu_read_lock_held() from lockdep expression since it is
> > > implicitly checked.
> > > - Remove unintended macro usage.
> > >
> > > v2:
> > > - Fix sparse error
> > > CHECK: Alignment should match open parenthesis
> > >
> > > drivers/char/ipmi/ipmi_msghandler.c | 14 ++++++++++----
> > > 1 file changed, 10 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> > > index cad9563f8f48..64ba16dcb681 100644
> > > --- a/drivers/char/ipmi/ipmi_msghandler.c
> > > +++ b/drivers/char/ipmi/ipmi_msghandler.c
> > > @@ -618,6 +618,8 @@ static DEFINE_MUTEX(ipmidriver_mutex);
> > >
> > > static LIST_HEAD(ipmi_interfaces);
> > > static DEFINE_MUTEX(ipmi_interfaces_mutex);
> > > +#define ipmi_interfaces_mutex_held() \
> > > + lockdep_is_held(&ipmi_interfaces_mutex)
> > > static struct srcu_struct ipmi_interfaces_srcu;
> > >
> > > /*
> > > @@ -1321,7 +1323,8 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
> > > * synchronize_srcu()) then free everything in that list.
> > > */
> > > mutex_lock(&intf->cmd_rcvrs_mutex);
> > > - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> > > + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> > > + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> > > if (rcvr->user == user) {
> > > list_del_rcu(&rcvr->link);
> > > rcvr->next = rcvrs;
> > > @@ -1599,7 +1602,8 @@ static struct cmd_rcvr *find_cmd_rcvr(struct ipmi_smi *intf,
> > > {
> > > struct cmd_rcvr *rcvr;
> > >
> > > - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> > > + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> > > + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> > > if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
> > > && (rcvr->chans & (1 << chan)))
> > > return rcvr;
> > > @@ -1614,7 +1618,8 @@ static int is_cmd_rcvr_exclusive(struct ipmi_smi *intf,
> > > {
> > > struct cmd_rcvr *rcvr;
> > >
> > > - list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
> > > + list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
> > > + lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
> > > if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
> > > && (rcvr->chans & chans))
> > > return 0;
> > > @@ -3450,7 +3455,8 @@ int ipmi_add_smi(struct module *owner,
> > > /* Look for a hole in the numbers. */
> > > i = 0;
> > > link = &ipmi_interfaces;
> > > - list_for_each_entry_rcu(tintf, &ipmi_interfaces, link) {
> > > + list_for_each_entry_rcu(tintf, &ipmi_interfaces, link,
> > > + ipmi_interfaces_mutex_held()) {
> > > if (tintf->intf_num != i) {
> > > link = &tintf->link;
> > > break;
> > > --
> > > 2.24.1
> > >