On Mon, Dec 25, 2017 at 7:50 AM, Qi Hou <qi.hou@xxxxxxxxxxxxx> wrote: > I found this problem below, and I now understand why it happens, but I'm not > 100% sure what is the best way to fix it. > > When booting up with "threadirqs" in command line, all irq handlers of the DMA > controller pl330 will be threaded forcedly. These threads will race for the same > list, pl330->req_done. > > Before the callback, the spinlock was released. And after it, the spinlock was > taken. This opened an race window where another threaded irq handler could steal > the spinlock and be permitted to delete entries of the list, pl330->req_done. > The locking has been recently modified beyond recognition, so I can't tell why that part of code is the way it is. The safest and cleanest solution seems to be to not drop and re-aquire the lock. Cheers! -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
