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List:       linux-keyrings
Subject:    Re: [PATCH v5 1/2] IMA: Define workqueue for early boot "key" measurements
From:       Mimi Zohar <zohar () linux ! ibm ! com>
Date:       2019-12-20 12:53:06
Message-ID: 1576846386.5241.13.camel () linux ! ibm ! com
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On Thu, 2019-12-19 at 08:55 -0800, Lakshmi Ramasubramanian wrote:
> I am not sure if the mutex can be removed.
> 
> In ima_queue_key() we need to test the flag and add the key to the list 
> as an atomic operation:
> 
>   if (!test_bit())
>      insert_key_to_list
> 
> Suppose the if condition is true, but before we could insert the key to 
> the list, ima_process_queued_keys() runs and processes queued keys we'll 
> add the key to the list and never process it.
> 
> Is there an API in the kernel to test and add an entry to a list 
> atomically?

Ok, using test_and_set_bit() and test_bit() only helps, if we can get
rid of the mutex.   I'll queue these patches.

thanks,

Mimi

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