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    Subject[PATCH 4.9 18/87] powerpc/powernv: Fix NVRAM sleep in invalid context when crashing
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Nicholas Piggin <npiggin@gmail.com>

    commit c1d2a31397ec51f0370f6bd17b19b39152c263cb upstream.

    Similarly to opal_event_shutdown, opal_nvram_write can be called in
    the crash path with irqs disabled. Special case the delay to avoid
    sleeping in invalid context.

    Fixes: 3b8070335f75 ("powerpc/powernv: Fix OPAL NVRAM driver OPAL_BUSY loops")
    Cc: stable@vger.kernel.org # v3.2
    Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/powerpc/platforms/powernv/opal-nvram.c | 14 ++++++++++++--
    1 file changed, 12 insertions(+), 2 deletions(-)

    --- a/arch/powerpc/platforms/powernv/opal-nvram.c
    +++ b/arch/powerpc/platforms/powernv/opal-nvram.c
    @@ -44,6 +44,10 @@ static ssize_t opal_nvram_read(char *buf
    return count;
    }

    +/*
    + * This can be called in the panic path with interrupts off, so use
    + * mdelay in that case.
    + */
    static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
    {
    s64 rc = OPAL_BUSY;
    @@ -58,10 +62,16 @@ static ssize_t opal_nvram_write(char *bu
    while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
    rc = opal_write_nvram(__pa(buf), count, off);
    if (rc == OPAL_BUSY_EVENT) {
    - msleep(OPAL_BUSY_DELAY_MS);
    + if (in_interrupt() || irqs_disabled())
    + mdelay(OPAL_BUSY_DELAY_MS);
    + else
    + msleep(OPAL_BUSY_DELAY_MS);
    opal_poll_events(NULL);
    } else if (rc == OPAL_BUSY) {
    - msleep(OPAL_BUSY_DELAY_MS);
    + if (in_interrupt() || irqs_disabled())
    + mdelay(OPAL_BUSY_DELAY_MS);
    + else
    + msleep(OPAL_BUSY_DELAY_MS);
    }
    }


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