Messages in this thread | | | Date | Wed, 16 Aug 2023 01:52:25 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH] dma-debug: defer __dma_entry_alloc_check_leak() printk output |
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On (23/08/15 17:42), Robin Murphy wrote: > On 15/08/2023 4:26 pm, Sergey Senozhatsky wrote: > > __dma_entry_alloc_check_leak() calls printk -> serial console > > output (qcom geni) and grabs port->lock under free_entries_lock, > > which is a conflicting locking dependency chain as qcom_geni IRQ > > handler can call into dma-debug code and grab free_entries_lock > > under port->lock. > > > > Use deferred printk in __dma_entry_alloc_check_leak() so that we > > don't acquire serial console's port->lock under free_entries_lock. > > Hmm, the print really doesn't need to be under the lock anyway, it only > needs to key off whether the "num_free_entries == 0" condition was hit or > not.
I thought about it, briefly. __dma_entry_alloc_check_leak() reads global nr_total_entries / nr_prealloc_entries which are updated (inc/dec) under free_entries_lock, so I didn't want to move __dma_entry_alloc_check_leak() outside of free_entries_lock scope.
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