linux-kernel - [PATCH] firewire: core: do not disable local IRQs while handling requests

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Message-ID: <20120218204200.759e2dd1@stein>
Date:	Sat, 18 Feb 2012 20:42:00 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	linux1394-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] firewire: core: do not disable local IRQs while handling
 requests

fw_core_handle_request() is called by the low-level driver in tasklet
context or process context, and fw_core_add/remove_address_handler() is
called by mid- or high-level code in process context.  So convert
address_handler_lock accesses from those which disable local IRQs to
ones which just disable local softIRQs.

Signed-off-by: Stefan Richter <stefanr@...6.in-berlin.de>
---
Only lightly tested without lockdep; I have yet to boot back into a
lockdep-enabled kernel.

Also to do:  Convert accesses of other locks of this kind, e.g. in
isochronous I/O handlers, and convert high-level code too.

 drivers/firewire/core-transaction.c |   21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

--- a/drivers/firewire/core-transaction.c
+++ b/drivers/firewire/core-transaction.c
@@ -565,7 +565,6 @@ int fw_core_add_address_handler(struct f
 				const struct fw_address_region *region)
 {
 	struct fw_address_handler *other;
-	unsigned long flags;
 	int ret = -EBUSY;
 
 	if (region->start & 0xffff000000000003ULL ||
@@ -575,7 +574,7 @@ int fw_core_add_address_handler(struct f
 	    handler->length == 0)
 		return -EINVAL;
 
-	spin_lock_irqsave(&address_handler_lock, flags);
+	spin_lock_bh(&address_handler_lock);
 
 	handler->offset = region->start;
 	while (handler->offset + handler->length <= region->end) {
@@ -594,7 +593,7 @@ int fw_core_add_address_handler(struct f
 		}
 	}
 
-	spin_unlock_irqrestore(&address_handler_lock, flags);
+	spin_unlock_bh(&address_handler_lock);
 
 	return ret;
 }
@@ -608,11 +607,9 @@ EXPORT_SYMBOL(fw_core_add_address_handle
  */
 void fw_core_remove_address_handler(struct fw_address_handler *handler)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&address_handler_lock, flags);
+	spin_lock_bh(&address_handler_lock);
 	list_del(&handler->link);
-	spin_unlock_irqrestore(&address_handler_lock, flags);
+	spin_unlock_bh(&address_handler_lock);
 }
 EXPORT_SYMBOL(fw_core_remove_address_handler);
 
@@ -829,7 +826,6 @@ static void handle_exclusive_region_requ
 					    unsigned long long offset)
 {
 	struct fw_address_handler *handler;
-	unsigned long flags;
 	int tcode, destination, source;
 
 	destination = HEADER_GET_DESTINATION(p->header[0]);
@@ -838,7 +834,7 @@ static void handle_exclusive_region_requ
 	if (tcode == TCODE_LOCK_REQUEST)
 		tcode = 0x10 + HEADER_GET_EXTENDED_TCODE(p->header[3]);
 
-	spin_lock_irqsave(&address_handler_lock, flags);
+	spin_lock_bh(&address_handler_lock);
 	handler = lookup_enclosing_address_handler(&address_handler_list,
 						   offset, request->length);
 	if (handler)
@@ -847,7 +843,7 @@ static void handle_exclusive_region_requ
 					  p->generation, offset,
 					  request->data, request->length,
 					  handler->callback_data);
-	spin_unlock_irqrestore(&address_handler_lock, flags);
+	spin_unlock_bh(&address_handler_lock);
 
 	if (!handler)
 		fw_send_response(card, request, RCODE_ADDRESS_ERROR);
@@ -859,7 +855,6 @@ static void handle_fcp_region_request(st
 				      unsigned long long offset)
 {
 	struct fw_address_handler *handler;
-	unsigned long flags;
 	int tcode, destination, source;
 
 	if ((offset != (CSR_REGISTER_BASE | CSR_FCP_COMMAND) &&
@@ -881,7 +876,7 @@ static void handle_fcp_region_request(st
 		return;
 	}
 
-	spin_lock_irqsave(&address_handler_lock, flags);
+	spin_lock_bh(&address_handler_lock);
 	list_for_each_entry(handler, &address_handler_list, link) {
 		if (is_enclosing_handler(handler, offset, request->length))
 			handler->address_callback(card, NULL, tcode,
@@ -891,7 +886,7 @@ static void handle_fcp_region_request(st
 						  request->length,
 						  handler->callback_data);
 	}
-	spin_unlock_irqrestore(&address_handler_lock, flags);
+	spin_unlock_bh(&address_handler_lock);
 
 	fw_send_response(card, request, RCODE_COMPLETE);
 }


-- 
Stefan Richter
-=====-===-- --=- =--=-
http://arcgraph.de/sr/
--
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