From 4d50c44381c981c9caa74e82ab894d4938dac9ca Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Thu, 27 Sep 2012 21:46:09 +0200 Subject: firewire: addendum to address handler RCU conversion Follow up on commit c285f6ff6787 "firewire: remove global lock around address handlers, convert to RCU": - address_handler_lock no longer serializes the address handler, only its function to serialize updates to the list of handlers remains. Rename the lock to address_handler_list_lock. - Callers of fw_core_remove_address_handler() must be able to sleep. Comment on this in the API documentation. - The counterpart fw_core_add_address_handler() is by nature something which is used in process context. Replace spin_lock_bh() by spin_lock() in fw_core_add_address_handler() and in fw_core_remove_address_handler(), and document that process context is now required for fw_core_add_address_handler(). - Extend the documentation of fw_address_callback_t. Signed-off-by: Stefan Richter --- include/linux/firewire.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/firewire.h b/include/linux/firewire.h index db04ec5121cb..191501afd7fb 100644 --- a/include/linux/firewire.h +++ b/include/linux/firewire.h @@ -265,8 +265,16 @@ typedef void (*fw_transaction_callback_t)(struct fw_card *card, int rcode, void *data, size_t length, void *callback_data); /* - * Important note: Except for the FCP registers, the callback must guarantee - * that either fw_send_response() or kfree() is called on the @request. + * This callback handles an inbound request subaction. It is called in + * RCU read-side context, therefore must not sleep. + * + * The callback should not initiate outbound request subactions directly. + * Otherwise there is a danger of recursion of inbound and outbound + * transactions from and to the local node. + * + * The callback is responsible that either fw_send_response() or kfree() + * is called on the @request, except for FCP registers for which the core + * takes care of that. */ typedef void (*fw_address_callback_t)(struct fw_card *card, struct fw_request *request, -- cgit v1.2.3