On Mon, 2015-01-19 at 09:47 +1100, Gavin Shan wrote:
> On pseries platform, the EEH reset backend pseries_eeh_reset() can
> be called in atomic context as follows. For this case, we should
> call udelay() instead of msleep() to avoid context switching.
>
> drivers/scsi/ipr.c::ipr_reset_slot_reset_done()
> drivers/pci/pci.c::pci_set_pcie_reset_state()
> arch/powerpc/kernel/eeh.c::pcibios_set_pcie_reset_state()
> arch/powerpc/platforms/pseries/eeh_pseries.c::pseries_eeh_reset()
It's not acceptable to introduce multi-millisecond delays at interrupt
time. In fact, we should generally not use udelay in such context.
I understand that this is an exceptional error handling case but it's
still not right.
Are there many other users of pci_set_pcie_reset_state() at interrupt
time ? Can we have a discussion with the PCI folks as to whether that
should be legal or not ?
I'm tempted to require that it's made illegal.
Ben.
> Signed-off-by: Gavin Shan <gws...@linux.vnet.ibm.com>
> Tested-by: Wen Xiong<wenxi...@linux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/pseries/eeh_pseries.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c
> b/arch/powerpc/platforms/pseries/eeh_pseries.c
> index a6c7e19..67623a3 100644
> --- a/arch/powerpc/platforms/pseries/eeh_pseries.c
> +++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
> @@ -503,8 +503,7 @@ static int pseries_eeh_get_state(struct eeh_pe *pe, int
> *state)
> */
> static int pseries_eeh_reset(struct eeh_pe *pe, int option)
> {
> - int config_addr;
> - int ret;
> + int config_addr, delay, ret;
>
> /* Figure out PE address */
> config_addr = pe->config_addr;
> @@ -528,9 +527,14 @@ static int pseries_eeh_reset(struct eeh_pe *pe, int
> option)
> /* We need reset hold or settlement delay */
> if (option == EEH_RESET_FUNDAMENTAL ||
> option == EEH_RESET_HOT)
> - msleep(EEH_PE_RST_HOLD_TIME);
> + delay = EEH_PE_RST_HOLD_TIME;
> + else
> + delay = EEH_PE_RST_SETTLE_TIME;
> +
> + if (in_atomic())
> + udelay(delay * 1000);
> else
> - msleep(EEH_PE_RST_SETTLE_TIME);
> + msleep(delay);
>
> return ret;
> }
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