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From:   Kalle Valo <kvalo@codeaurora.org>
To:     Jiri Kosina <jikos@kernel.org>
Cc:     Luca Coelho <luciano.coelho@intel.com>,
        Johannes Berg <johannes.berg@intel.com>,
        Emmanuel Grumbach <emmanuel.grumbach@intel.com>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iwlwifi: mvm: protect regulatory_set_wiphy_regd_sync() with wiphy lock
References: <nycvar.YFH.7.76.2111232204150.16505@cbobk.fhfr.pm>
Date:   Wed, 24 Nov 2021 10:10:25 +0200
In-Reply-To: <nycvar.YFH.7.76.2111232204150.16505@cbobk.fhfr.pm> (Jiri
        Kosina's message of "Tue, 23 Nov 2021 22:06:19 +0100 (CET)")
Message-ID: <871r366kjy.fsf@codeaurora.org>
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Jiri Kosina <jikos@kernel.org> writes:

> From: Jiri Kosina <jkosina@suse.cz>
>
> Since the switch away from rtnl to wiphy lock, 
> regulatory_set_wiphy_regd_sync() has to be called with wiphy lock held; 
> this is currently not the case on the module load codepath.
>
> Fix that by properly acquiring it in iwl_mvm_start_get_nvm() to maintain 
> also lock ordering against mvm->mutex and RTNL.
>
> This fixes the splat below.
>
>  =============================
>  WARNING: suspicious RCU usage
>  5.16.0-rc2 #1 Not tainted
>  -----------------------------
>  drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c:264 suspicious rcu_dereference_protected() usage!
>
>  other info that might help us debug this:
>
>  rcu_scheduler_active = 2, debug_locks = 1
>  3 locks held by modprobe/578:
>   #0: ffffffffc0b6f0e8 (iwlwifi_opmode_table_mtx){+.+.}-{3:3}, at: iwl_opmode_register+0x2e/0xe0 [iwlwifi]
>   #1: ffffffff9a856b08 (rtnl_mutex){+.+.}-{3:3}, at: iwl_op_mode_mvm_start+0xa0b/0xcb0 [iwlmvm]
>   #2: ffff8e5242f53380 (&mvm->mutex){+.+.}-{3:3}, at: iwl_op_mode_mvm_start+0xa16/0xcb0 [iwlmvm]
>
>  stack backtrace:
>  CPU: 1 PID: 578 Comm: modprobe Not tainted 5.16.0-rc2 #1
>  Hardware name: LENOVO 20K5S22R00/20K5S22R00, BIOS R0IET38W (1.16 ) 05/31/2017
>  Call Trace:
>   <TASK>
>   dump_stack_lvl+0x58/0x71
>   iwl_mvm_init_fw_regd+0x13d/0x180 [iwlmvm]
>   iwl_mvm_init_mcc+0x66/0x1d0 [iwlmvm]
>   iwl_op_mode_mvm_start+0xc6d/0xcb0 [iwlmvm]
>   _iwl_op_mode_start.isra.4+0x42/0x80 [iwlwifi]
>   iwl_opmode_register+0x71/0xe0 [iwlwifi]
>   ? 0xffffffffc1062000
>   iwl_mvm_init+0x34/0x1000 [iwlmvm]
>   do_one_initcall+0x5b/0x300
>   do_init_module+0x5b/0x21c
>   load_module+0x1b2f/0x2320
>   ? __do_sys_finit_module+0xaa/0x110
>   __do_sys_finit_module+0xaa/0x110
>   do_syscall_64+0x3a/0xb0
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
>  RIP: 0033:0x7f7cdd7c8ded
>  Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d fb ef 0e 00 f7 d8 64 89 01 48
>  RSP: 002b:00007fffb90bf458 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
>  RAX: ffffffffffffffda RBX: 0000559c501caf00 RCX: 00007f7cdd7c8ded
>  RDX: 0000000000000000 RSI: 0000559c4eb366ee RDI: 0000000000000002
>  RBP: 0000000000040000 R08: 0000000000000000 R09: 0000559c501ca9f8
>  R10: 0000000000000002 R11: 0000000000000246 R12: 0000559c4eb366ee
>  R13: 0000559c501cadb0 R14: 0000000000000000 R15: 0000559c501cbad0
>   </TASK>
>  ------------[ cut here ]------------
>  WARNING: CPU: 1 PID: 578 at net/wireless/reg.c:3107 reg_process_self_managed_hint+0x183/0x1d0 [cfg80211]
>  Modules linked in:
>  CPU: 1 PID: 578 Comm: modprobe Not tainted 5.16.0-rc2 #1
>  Hardware name: LENOVO 20K5S22R00/20K5S22R00, BIOS R0IET38W (1.16 ) 05/31/2017
>  RIP: 0010:reg_process_self_managed_hint+0x183/0x1d0 [cfg80211]
>  Code: 83 c4 60 5b 41 5a 41 5c 41 5d 41 5e 41 5f 5d 49 8d 62 f8 c3 48 8d 7b 68 be ff ff ff ff e8 75 4a 13 d9 85 c0 0f 85 e6 fe ff ff <0f> 0b e9 df fe ff ff 0f 0b 80 3d bc 2c 0b 00 00 0f 85 c2 fe ff ff
>  RSP: 0018:ffff9994809cfaf0 EFLAGS: 00010246
>  RAX: 0000000000000000 RBX: ffff8e5242f505c0 RCX: 0000000000000000
>  RDX: 0000000000000000 RSI: ffff8e5242f50628 RDI: ffff8e524a2b5cd0
>  RBP: ffff9994809cfb80 R08: 0000000000000001 R09: ffffffff9b2e2f50
>  R10: ffff9994809cfb98 R11: ffffffffffffffff R12: 0000000000000000
>  R13: ffff8e5242f532e8 R14: ffff8e5248914010 R15: ffff8e5242f532e0
>  FS:  00007f7cdd6af740(0000) GS:ffff8e5367480000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 00007f19430687ac CR3: 00000001088fa003 CR4: 00000000003706e0
>  Call Trace:
>   <TASK>
>   ? lock_is_held_type+0xb4/0x120
>   ? regulatory_set_wiphy_regd_sync+0x2f/0x80 [cfg80211]
>   regulatory_set_wiphy_regd_sync+0x2f/0x80 [cfg80211]
>   iwl_mvm_init_mcc+0xcd/0x1d0 [iwlmvm]
>   iwl_op_mode_mvm_start+0xc6d/0xcb0 [iwlmvm]
>   _iwl_op_mode_start.isra.4+0x42/0x80 [iwlwifi]
>   iwl_opmode_register+0x71/0xe0 [iwlwifi]
>   ? 0xffffffffc1062000
>   iwl_mvm_init+0x34/0x1000 [iwlmvm]
>   do_one_initcall+0x5b/0x300
>   do_init_module+0x5b/0x21c
>   load_module+0x1b2f/0x2320
>   ? __do_sys_finit_module+0xaa/0x110
>   __do_sys_finit_module+0xaa/0x110
>   do_syscall_64+0x3a/0xb0
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
>  RIP: 0033:0x7f7cdd7c8ded
>  Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d fb ef 0e 00 f7 d8 64 89 01 48
>  RSP: 002b:00007fffb90bf458 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
>  RAX: ffffffffffffffda RBX: 0000559c501caf00 RCX: 00007f7cdd7c8ded
>  RDX: 0000000000000000 RSI: 0000559c4eb366ee RDI: 0000000000000002
>  RBP: 0000000000040000 R08: 0000000000000000 R09: 0000559c501ca9f8
>  R10: 0000000000000002 R11: 0000000000000246 R12: 0000559c4eb366ee
>  R13: 0000559c501cadb0 R14: 0000000000000000 R15: 0000559c501cbad0
>
> Fixes: a05829a7222e9d1 ("cfg80211: avoid holding the RTNL when calling the driver")
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>

I think this should go to wireless-drivers so I assigned this to me.
Luca, ack?

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