linux-kernel - [PATCH] nubus: Remove proc entries before adding them

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Message-Id: <dd1b560bbe426b351cdbb3bbf89414753c3d0117.1679446472.git.fthain@linux-m68k.org>
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: Remove proc entries before adding them

The config ROMs on some Nubus cards contain mistakes such as resource
duplication. This results in a warning from proc_register():

[    1.660000] NuBus: Scanning NuBus slots.
[    1.740000] ------------[ cut here ]------------
[    1.750000] WARNING: CPU: 0 PID: 1 at fs/proc/generic.c:376 proc_register+0xbc/0xda
[    1.770000] proc_dir_entry '24/5' already registered
[    1.790000] Modules linked in:
[    1.800000] CPU: 0 PID: 1 Comm: swapper Not tainted 6.1.0-5-m68k #1  Debian 6.1.12-1
[    1.800000] Stack from 00829d18:
[    1.800000]         00829d18 00451507 00451507 00000000 00000009 0038c57c 00451507 00386bae
[    1.800000]         00442945 0045f062 00000178 00868580 00868f50 00386c42 0045f062 00000178
[    1.800000]         00166fc8 00000009 00000000 00829d78 008685e4 0037f9ec 00000025 00248808
[    1.800000]         0045f0df 00829d94 00166fc8 0045f062 00000178 00000009 0045f0df 008689e4
[    1.800000]         008685e4 fafe3a20 00868980 00829df3 00829e32 00000024 00829dc0 00167332
[    1.800000]         00868980 00868580 00829e40 00248d36 00829df3 00008124 00868980 00248b0c
[    1.800000] Call Trace: [<0038c57c>] dump_stack+0xc/0x10
[    1.800000]  [<00386bae>] __warn+0x70/0xbc
[    1.800000]  [<00386c42>] warn_slowpath_fmt+0x48/0x66
[    1.800000]  [<00166fc8>] proc_register+0xbc/0xda
[    1.800000]  [<0037f9ec>] memcmp+0x0/0x56
[    1.800000]  [<00248808>] nubus_get_rsrc_str+0x0/0x5e
[    1.800000]  [<00166fc8>] proc_register+0xbc/0xda
[    1.800000]  [<00167332>] proc_create_single_data+0x40/0x48
[    1.800000]  [<00248d36>] nubus_proc_add_rsrc_mem+0x68/0xa4
[    1.800000]  [<00008124>] amiga_mksound+0xb8/0xc8
[    1.800000]  [<00248b0c>] nubus_proc_rsrc_show+0x0/0xa4
[    1.800000]  [<00386180>] memset+0x0/0x94
[    1.800000]  [<0024864a>] nubus_readdir+0x0/0x66
[    1.800000]  [<00560f35>] nubus_get_vendorinfo.isra.0+0x87/0x10e
[    1.800000]  [<00560fb4>] nubus_get_vendorinfo.isra.0+0x106/0x10e
[    1.800000]  [<00248d72>] nubus_proc_add_rsrc+0x0/0x8e
[    1.800000]  [<001f6f50>] __dynamic_pr_debug+0x0/0x96
[    1.800000]  [<0038741e>] _printk+0x0/0x18
[    1.800000]  [<0016fafe>] kernfs_link_sibling+0x9a/0xaa
[    1.800000]  [<00561cb0>] nubus_init+0x660/0x79c
[    1.800000]  [<0037f7c6>] strcpy+0x0/0x1c
[    1.800000]  [<0003f58c>] parse_args+0x0/0x308
[    1.800000]  [<00002104>] do_one_initcall+0x0/0x184
[    1.800000]  [<00561650>] nubus_init+0x0/0x79c
[    1.800000]  [<00010000>] frc1_dst+0xe/0x14
[    1.800000]  [<00002172>] do_one_initcall+0x6e/0x184
[    1.800000]  [<0037f7c6>] strcpy+0x0/0x1c
[    1.800000]  [<0003f58c>] parse_args+0x0/0x308
[    1.800000]  [<00002104>] do_one_initcall+0x0/0x184
[    1.800000]  [<0054b25c>] kernel_init_freeable+0x192/0x19c
[    1.800000]  [<00561650>] nubus_init+0x0/0x79c
[    1.800000]  [<0038c6c4>] kernel_init+0x0/0xec
[    1.800000]  [<0038c6d8>] kernel_init+0x14/0xec
[    1.800000]  [<0038c6c4>] kernel_init+0x0/0xec
[    1.800000]  [<0000297c>] ret_from_kernel_thread+0xc/0x14
[    1.800000]
[    1.810000] ---[ end trace 0000000000000000 ]---

This particular card (a Radius video card) contains a duplicated resource
hence the /proc/bus/nubus/a/1/24/5 entry got registered twice.
(A date resource has ID 5, the vendor info directory has ID 24)

The solution for this is to remove a potentially pre-existing entry before
adding the procfs entry for the resource.

Reported-and-tested-by: Stan Johnson <userm57@...oo.com>
Signed-off-by: Finn Thain <fthain@...ux-m68k.org>
---
This patch should be applied after "nubus: Partially revert
proc_create_single_data() conversion".
---
 drivers/nubus/proc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/nubus/proc.c b/drivers/nubus/proc.c
index cd4bd06cf309..2c320a84fd72 100644
--- a/drivers/nubus/proc.c
+++ b/drivers/nubus/proc.c
@@ -75,6 +75,7 @@ struct proc_dir_entry *nubus_proc_add_rsrc_dir(struct proc_dir_entry *procdir,
 	if (!procdir)
 		return NULL;
 	snprintf(name, sizeof(name), "%x", ent->type);
+	remove_proc_subtree(name, procdir);
 	return proc_mkdir_data(name, 0555, procdir, (void *)lanes);
 }
 
@@ -164,6 +165,7 @@ void nubus_proc_add_rsrc_mem(struct proc_dir_entry *procdir,
 		pded = nubus_proc_alloc_pde_data(nubus_dirptr(ent), size);
 	else
 		pded = NULL;
+	remove_proc_subtree(name, procdir);
 	proc_create_data(name, S_IFREG | 0444, procdir,
 			 &nubus_rsrc_proc_ops, pded);
 }
@@ -178,6 +180,7 @@ void nubus_proc_add_rsrc(struct proc_dir_entry *procdir,
 		return;
 
 	snprintf(name, sizeof(name), "%x", ent->type);
+	remove_proc_subtree(name, procdir);
 	proc_create_data(name, S_IFREG | 0444, procdir,
 			 &nubus_rsrc_proc_ops,
 			 nubus_proc_alloc_pde_data(data, 0));
-- 
2.37.5