[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Re: [PATCH] IRQ handling race and spurious IIR read in serial/8250.c
Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> writes: > I wrote: >> In drivers/serial/8250.c in Linux there are two bugs: >> 1. UART_BUG_TXEN can be spuriously set, due to an IRQ race >> 2. The workaround then applied by the kernel is itself buggy > > Markus Armbruster has also experienced this problem in a Xen > environment and has confirmed that my patch fixes it. Correct. > I think at the very least this change: > >> Proposed initial band-aid fix (against 2.6.28.4): >> >> Do not read IIR in serial8250_start_tx when UART_BUG_TXEN >> >> Reading the IIR clears some oustanding interrupts so it is not safe. >> Instead, simply transmit immediately if the buffer is empty without >> regard to IIR. >> >> Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx> > > should be made right away. > > Ian. Patch makes sense to me. Acked-by: Markus Armbruster <armbru@xxxxxxxxxx> _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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