[Linux-kernel-mentees] [PATCH] drivers: firewire: core-transaction: Pass lockdep condition to address_handler_list iterator

[Linux-kernel-mentees] [PATCH] drivers: firewire: core-transaction: Pass lockdep condition to address_handler_list iterator

[madhuparnabhowmik04]

From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>

The address_handler_list is traversed with list_for_each_entry_rcu
with address_handler_list_lock held.
list_for_each_entry_rcu has built-in RCU and lock checking.
Use it for address_handler_list traversal.

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
---
 drivers/firewire/core-transaction.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c
index 404a035f104d..a15e70027932 100644
--- a/drivers/firewire/core-transaction.c
+++ b/drivers/firewire/core-transaction.c
@@ -61,6 +61,11 @@
 #define PHY_CONFIG_ROOT_ID(node_id)	((((node_id) & 0x3f) << 24) | (1 << 23))
 #define PHY_IDENTIFIER(id)		((id) << 30)
 
+static DEFINE_SPINLOCK(address_handler_list_lock);
+static LIST_HEAD(address_handler_list);
+
+#define address_handler_list_lock_held() lock_is_held(&(address_handler_list_lock).dep_map)
+
 /* returns 0 if the split timeout handler is already running */
 static int try_cancel_split_timeout(struct fw_transaction *t)
 {
@@ -485,7 +490,7 @@ static struct fw_address_handler *lookup_overlapping_address_handler(
 {
 	struct fw_address_handler *handler;
 
-	list_for_each_entry_rcu(handler, list, link) {
+	list_for_each_entry_rcu(handler, list, link, address_handler_list_lock_held()) {
 		if (handler->offset < offset + length &&
 		    offset < handler->offset + handler->length)
 			return handler;
@@ -514,8 +519,6 @@ static struct fw_address_handler *lookup_enclosing_address_handler(
 	return NULL;
 }
 
-static DEFINE_SPINLOCK(address_handler_list_lock);
-static LIST_HEAD(address_handler_list);
 
 const struct fw_address_region fw_high_memory_region =
 	{ .start = FW_MAX_PHYSICAL_RANGE, .end = 0xffffe0000000ULL, };
-- 
2.17.1

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

Re: [Linux-kernel-mentees] [PATCH] drivers: firewire: core-transaction: Pass lockdep condition to address_handler_list iterator

[Joel Fernandes]

On Sat, Jan 04, 2020 at 08:12:15PM +0530, madhuparnabhowmik04@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
> 
> The address_handler_list is traversed with list_for_each_entry_rcu
> with address_handler_list_lock held.
> list_for_each_entry_rcu has built-in RCU and lock checking.
> Use it for address_handler_list traversal.
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>

Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>

thanks,

 - Joel

> ---
>  drivers/firewire/core-transaction.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c
> index 404a035f104d..a15e70027932 100644
> --- a/drivers/firewire/core-transaction.c
> +++ b/drivers/firewire/core-transaction.c
> @@ -61,6 +61,11 @@
>  #define PHY_CONFIG_ROOT_ID(node_id)	((((node_id) & 0x3f) << 24) | (1 << 23))
>  #define PHY_IDENTIFIER(id)		((id) << 30)
>  
> +static DEFINE_SPINLOCK(address_handler_list_lock);
> +static LIST_HEAD(address_handler_list);
> +
> +#define address_handler_list_lock_held() lock_is_held(&(address_handler_list_lock).dep_map)
> +
>  /* returns 0 if the split timeout handler is already running */
>  static int try_cancel_split_timeout(struct fw_transaction *t)
>  {
> @@ -485,7 +490,7 @@ static struct fw_address_handler *lookup_overlapping_address_handler(
>  {
>  	struct fw_address_handler *handler;
>  
> -	list_for_each_entry_rcu(handler, list, link) {
> +	list_for_each_entry_rcu(handler, list, link, address_handler_list_lock_held()) {
>  		if (handler->offset < offset + length &&
>  		    offset < handler->offset + handler->length)
>  			return handler;
> @@ -514,8 +519,6 @@ static struct fw_address_handler *lookup_enclosing_address_handler(
>  	return NULL;
>  }
>  
> -static DEFINE_SPINLOCK(address_handler_list_lock);
> -static LIST_HEAD(address_handler_list);
>  
>  const struct fw_address_region fw_high_memory_region =
>  	{ .start = FW_MAX_PHYSICAL_RANGE, .end = 0xffffe0000000ULL, };
> -- 
> 2.17.1
> 
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees