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Sun, 3 Aug 2025 08:20:22 -0400 (EDT) From: Takashi Sakamoto To: linux1394-devel@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org Subject: [PATCH v2 2/4] firewire: core: call handler for exclusive regions outside RCU read-side critical section Date: Sun, 3 Aug 2025 21:20:13 +0900 Message-ID: <20250803122015.236493-3-o-takashi@sakamocchi.jp> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250803122015.236493-1-o-takashi@sakamocchi.jp> References: <20250803122015.236493-1-o-takashi@sakamocchi.jp> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The previous commit added reference counting to ensure safe invocations of address handlers. This commit moves the invocation of handlers for exclusive regions outside of the RCU read-side critical section. The address handler for the requested region is selected within the critical section, then invoked outside of it. Signed-off-by: Takashi Sakamoto --- drivers/firewire/core-transaction.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-tr= ansaction.c index 29ca9f3f14ce..a742971c65fa 100644 --- a/drivers/firewire/core-transaction.c +++ b/drivers/firewire/core-transaction.c @@ -935,17 +935,19 @@ static void handle_exclusive_region_request(struct fw= _card *card, scoped_guard(rcu) { handler =3D lookup_enclosing_address_handler(&address_handler_list, offs= et, request->length); - if (handler) { + if (handler) get_address_handler(handler); - handler->address_callback(card, request, tcode, destination, source, - p->generation, offset, request->data, - request->length, handler->callback_data); - put_address_handler(handler); - } } =20 - if (!handler) + if (!handler) { fw_send_response(card, request, RCODE_ADDRESS_ERROR); + return; + } + + // Outside the RCU read-side critical section. Without spinlock. With ref= erence count. + handler->address_callback(card, request, tcode, destination, source, p->g= eneration, offset, + request->data, request->length, handler->callback_data); + put_address_handler(handler); } =20 static void handle_fcp_region_request(struct fw_card *card, --=20 2.48.1