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Message-ID: <25196a3d-865f-8329-0a91-aa74dd0308c0@linux.ibm.com>
Date:   Thu, 8 Jun 2023 11:45:49 -0500
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Subject: Re: [PATCH 1/2] fsi: core: Lock scan mutex for master index removal
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To:     Joel Stanley <joel@jms.id.au>
Cc:     linux-fsi@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        jk@ozlabs.org, alistair@popple.id.au
References: <20230412185602.1592629-1-eajames@linux.ibm.com>
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From:   Eddie James <eajames@linux.ibm.com>
In-Reply-To: <CACPK8XcK7s44VzkDyA6O3CKKGCfSsV=nmtwkf6YwV-9ZDAx63A@mail.gmail.com>
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On 5/31/23 02:47, Joel Stanley wrote:
> On Wed, 12 Apr 2023 at 18:56, Eddie James <eajames@linux.ibm.com> wrote:
>> If a master scan occurs while the master is being unregistered,
>> the devicecs may end up with incorrect and possibly duplicate names,
> typo: devices


Thanks...


>
>> resulting in kernel warnings. Ensure the master index isn't changed
>> outside of the scan mutex.
>>
>> Signed-off-by: Eddie James <eajames@linux.ibm.com>
>> ---
>>   drivers/fsi/fsi-core.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
>> index fcbf0469ce3f..18d4d68482d7 100644
>> --- a/drivers/fsi/fsi-core.c
>> +++ b/drivers/fsi/fsi-core.c
>> @@ -1354,12 +1354,12 @@ EXPORT_SYMBOL_GPL(fsi_master_register);
>>
>>   void fsi_master_unregister(struct fsi_master *master)
>>   {
>> +       mutex_lock(&master->scan_lock);
> The ida functions are supposed to not require locking, but protecting
> against the test and changing of ->idx makes sense.
>
> Do you want to add a Fixes: line?


Sure.


>
>>          if (master->idx >= 0) {
>>                  ida_simple_remove(&master_ida, master->idx);
> the ida_simple functions are depreciated, at some point we should
> replace them with ida_alloc/ida_free.


OK, I'll see if it makes sense to do that now.

Thanks!

Eddie


>
>>                  master->idx = -1;
>>          }
>>
>> -       mutex_lock(&master->scan_lock);
>>          fsi_master_unscan(master);
>>          mutex_unlock(&master->scan_lock);
>>          device_unregister(&master->dev);
>> --
>> 2.31.1
>>