Also,
On Tue, 2011-10-04 at 13:19 +0530, Ravi K Nittala wrote:
> The RTAS firmware flash update is conducted using an RTAS call that is
> serialized by lock_rtas() which uses spin_lock. While the flash is in
> progress, rtasd performs scan for any RTAS events that are generated by
> the system. rtasd keeps scanning for the RTAS events generated on the
> machine. This is performed via workqueue mechanism. The rtas_event_scan()
> also uses an RTAS call to scan the events, eventually trying to acquire
> the spin_lock before issuing the request.
>
> The flash update takes a while to complete and during this time, any other
> RTAS call has to wait. In this case, rtas_event_scan() waits for a long time
> on the spin_lock resulting in a soft lockup.
>
> Fix: Just before the flash update is performed, the queued rtas_event_scan()
> work item is cancelled from the work queue so that there is no other RTAS
> call issued while the flash is in progress. After the flash completes, the
> system reboots and the rtas_event_scan() is rescheduled.
>
> Signed-off-by: Suzuki Poulose <suz...@in.ibm.com>
> Signed-off-by: Ravi Nittala <ravi.nitt...@in.ibm.com>
Reported-by: Divya Vikas <divya.vi...@in.ibm.com>
Regards--
Subrata
>
> ---
> arch/powerpc/include/asm/rtas.h | 6 ++++++
> arch/powerpc/kernel/rtas_flash.c | 6 ++++++
> arch/powerpc/kernel/rtasd.c | 7 +++++++
> 3 files changed, 19 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
> index 58625d1..754723b 100644
> --- a/arch/powerpc/include/asm/rtas.h
> +++ b/arch/powerpc/include/asm/rtas.h
> @@ -245,6 +245,12 @@ extern int early_init_dt_scan_rtas(unsigned long node,
>
> extern void pSeries_log_error(char *buf, unsigned int err_type, int fatal);
>
> +#ifdef CONFIG_PPC_RTAS_DAEMON
> +extern void rtas_cancel_event_scan(void);
> +#else
> +static inline void rtas_cancel_event_scan(void) { }
> +#endif
> +
> /* Error types logged. */
> #define ERR_FLAG_ALREADY_LOGGED 0x0
> #define ERR_FLAG_BOOT 0x1 /* log was pulled from NVRAM on
> boot */
> diff --git a/arch/powerpc/kernel/rtas_flash.c
> b/arch/powerpc/kernel/rtas_flash.c
> index e037c74..4174b4b 100644
> --- a/arch/powerpc/kernel/rtas_flash.c
> +++ b/arch/powerpc/kernel/rtas_flash.c
> @@ -568,6 +568,12 @@ static void rtas_flash_firmware(int reboot_type)
> }
>
> /*
> + * Just before starting the firmware flash, cancel the event scan work
> + * to avoid any soft lockup issues.
> + */
> + rtas_cancel_event_scan();
> +
> + /*
> * NOTE: the "first" block must be under 4GB, so we create
> * an entry with no data blocks in the reserved buffer in
> * the kernel data segment.
> diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c
> index 481ef06..1045ff4 100644
> --- a/arch/powerpc/kernel/rtasd.c
> +++ b/arch/powerpc/kernel/rtasd.c
> @@ -472,6 +472,13 @@ static void start_event_scan(void)
> &event_scan_work, event_scan_delay);
> }
>
> +/* Cancel the rtas event scan work */
> +void rtas_cancel_event_scan(void)
> +{
> + cancel_delayed_work_sync(&event_scan_work);
> +}
> +EXPORT_SYMBOL_GPL(rtas_cancel_event_scan);
> +
> static int __init rtas_init(void)
> {
> struct proc_dir_entry *entry;
>
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