Messages in this thread | | | Date | Wed, 12 Feb 2020 13:49:56 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH v3] drivers: char: ipmi: ipmi_msghandler: Pass lockdep expression to RCU lists |
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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 <frextrite@gmail.com> > > After reading everything, I think this is correct, but I would like > Paul's stamp of approval on this.
Acked-by: Paul E. McKenney <paulmck@kernel.org>
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 > >
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