linux-kernel - RE: [PATCH printk-rework 09/14] printk: introduce a kmsg

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Date:   Fri, 19 Feb 2021 16:50:34 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     John Ogness <john.ogness@...utronix.de>,
        Petr Mladek <pmladek@...e.com>
CC:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH printk-rework 09/14] printk: introduce a kmsg_dump
 iterator

From: John Ogness <john.ogness@...utronix.de> Sent: Thursday, February 18, 2021 12:18 AM
> 
> Rather than store the iterator information into the registered
> kmsg_dump structure, create a separate iterator structure. The
> kmsg_dump_iter structure can reside on the stack of the caller,
> thus allowing lockless use of the kmsg_dump functions.
> 
> This is in preparation for removal of @logbuf_lock.
> 
> Signed-off-by: John Ogness <john.ogness@...utronix.de>
> ---
>  arch/powerpc/kernel/nvram_64.c             | 12 ++--
>  arch/powerpc/platforms/powernv/opal-kmsg.c |  3 +-
>  arch/powerpc/xmon/xmon.c                   |  6 +-
>  arch/um/kernel/kmsg_dump.c                 |  5 +-
>  drivers/hv/vmbus_drv.c                     |  5 +-
>  drivers/mtd/mtdoops.c                      |  5 +-
>  fs/pstore/platform.c                       |  5 +-
>  include/linux/kmsg_dump.h                  | 43 +++++++-------
>  kernel/debug/kdb/kdb_main.c                | 10 ++--
>  kernel/printk/printk.c                     | 65 +++++++++++-----------
>  10 files changed, 84 insertions(+), 75 deletions(-)
> 

[snip]

> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 4fad3e6745e5..fbeddef90941 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -1359,7 +1359,8 @@ static void vmbus_isr(void)
>   * buffer and call into Hyper-V to transfer the data.
>   */
>  static void hv_kmsg_dump(struct kmsg_dumper *dumper,
> -			 enum kmsg_dump_reason reason)
> +			 enum kmsg_dump_reason reason,
> +			 struct kmsg_dumper_iter *iter)
>  {
>  	size_t bytes_written;
>  	phys_addr_t panic_pa;
> @@ -1374,7 +1375,7 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper,
>  	 * Write dump contents to the page. No need to synchronize; panic should
>  	 * be single-threaded.
>  	 */
> -	kmsg_dump_get_buffer(dumper, false, hv_panic_page, HV_HYP_PAGE_SIZE,
> +	kmsg_dump_get_buffer(iter, false, hv_panic_page, HV_HYP_PAGE_SIZE,
>  			     &bytes_written);
>  	if (bytes_written)
>  		hyperv_report_panic_msg(panic_pa, bytes_written);

For the Hyper-V portion,

Reviewed-by: Michael Kelley <mikelley@...rosoft.com>