lkml.org 
[lkml]   [2020]   [Feb]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3] drivers: char: ipmi: ipmi_msghandler: Pass lockdep expression to RCU lists
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.

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
>

\
 
 \ /
  Last update: 2020-02-12 14:46    [W:0.109 / U:0.336 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site