linux-kernel - [PATCH] nubus: Avoid scanning "private" card resources

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Date:   Wed, 22 Mar 2023 11:54:32 +1100
From:   Finn Thain <fthain@...ux-m68k.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org
Subject: [PATCH] nubus: Avoid scanning "private" card resources

Some Nubus cards have many ROM resources. A single Radius video card
produced well over a thousand entries under /proc/bus/nubus. Populating
/proc/bus/nubus on a slow machine with several such cards installed takes
long enough that the user may think that the system is wedged. All those
procfs entries also consume significant RAM though they are not normally
needed except by developers. Omit the "private" resources from
/proc/bus/nubus/ by default and add a kernel parameter to enable them
when needed. On the test machine, this saved 196 KiB and 5 seconds.

Tested-by: Stan Johnson <userm57@...oo.com>
Signed-off-by: Finn Thain <fthain@...ux-m68k.org>
---
 drivers/nubus/nubus.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/nubus/nubus.c b/drivers/nubus/nubus.c
index f70ba58dbc55..777099b8e818 100644
--- a/drivers/nubus/nubus.c
+++ b/drivers/nubus/nubus.c
@@ -34,6 +34,9 @@

 LIST_HEAD(nubus_func_rsrcs);

+bool all_func_rsrcs;
+module_param(all_func_rsrcs, bool, 0444);
+
 /* Meaning of "bytelanes":

    The card ROM may appear on any or all bytes of each long word in
@@ -572,9 +575,9 @@ nubus_get_functional_resource(struct nubus_board *board, int slot,
 			nubus_proc_add_rsrc(dir.procdir, &ent);
 			break;
 		default:
-			/* Local/Private resources have their own
-			   function */
-			nubus_get_private_resource(fres, dir.procdir, &ent);
+			if (all_func_rsrcs)
+				nubus_get_private_resource(fres, dir.procdir,
+							   &ent);
 		}
 	}

-- 
2.37.5