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Date: Wed, 13 Feb 2008 11:36:38 -0600
From: James Bottomley <James.Bottomley@...senPartnership.com>
To: Boaz Harrosh <bharrosh@...asas.com>
Cc: Sven Köhler <skoehler@....de>,
Christoph Hellwig <hch@...radead.org>,
Jeff Garzik <jeff@...zik.org>,
linux-scsi <linux-scsi@...r.kernel.org>,
linux-kernel@...r.kernel.org, Joerg Dorchain <joerg@...chain.net>,
Jon Chelton <jchelton@...global.com>,
Stefan Priebe - allied internet ag
<s.priebe@...ied-internet.ag>
Subject: Re: [BUGFIX 2/2] gdth: bugfix for the Timer at exit crash
On Wed, 2008-02-13 at 19:12 +0200, Boaz Harrosh wrote:
> On Wed, Feb 13 2008 at 19:03 +0200, James Bottomley <James.Bottomley@...senPartnership.com> wrote:
> > On Wed, 2008-02-13 at 18:50 +0200, Boaz Harrosh wrote:
> >> On Wed, Feb 13 2008 at 18:45 +0200, James Bottomley <James.Bottomley@...senPartnership.com> wrote:
> >>> On Wed, 2008-02-13 at 18:33 +0200, Boaz Harrosh wrote:
> >>>> On Wed, Feb 13 2008 at 17:54 +0200, Boaz Harrosh <bharrosh@...asas.com> wrote:
> >>>>> On Wed, Feb 13 2008 at 17:44 +0200, James Bottomley <James.Bottomley@...senPartnership.com> wrote:
> >>>>>> On Tue, 2008-02-12 at 19:40 +0200, Boaz Harrosh wrote:
> >>>>>>> - gdth_flush(ha);
> >>>>>>> -
> >>>>>> This piece doesn't look right. gdth_flush() forces the internal cache
> >>>>>> to disk backing. If you remove it, you're taking the chance that the
> >>>>>> machine will be powered off without a writeback which can cause data
> >>>>>> corruption.
> >>>>>>
> >>>>>> James
> >>>>>>
> >>>>> Yes.
> >>>>> I have more problems reported, with exit, and am just sending one more patch that puts
> >>>>> this back in. Which was tested.
> >>>>>
> >>>>> So I will resend this one plus one new one.
> >>>>>
> >>>>> Boaz
> >>>>>
> >>>> The gdth driver would do a register_reboot_notifier(&gdth_notifier);
> >>>> to a gdth_halt() function, which would then redo half of what gdth_exit
> >>>> does, and wrongly so, and crash.
> >>>>
> >>>> Are we guaranteed in todays kernel that modules .exit function be called
> >>>> on an halt or reboot? If so then there is no need for duplications and
> >>>> the gdth_halt() should go.
> >>> No. The __exit section is actually discardable if you promise never to
> >>> remove the module.
> >>>
> >> I don't understand please explain.
> >> What does a driver need to do if it needs a consistent shutdown retine?
> >> module or built in? unload or shutdown?
> >
> > It needs to register a reboot notifier, which gdth does.
> >
> > However, the notifier is only called on reboot, so it also needs to
> > clean up correctly on module exit as well.
> >
> > The alternative for GDTH would be to process the SCSI SYNCHRONIZE CACHE
> > command. That's done by a shutdown notifier from sd, so the correct
> > thing would always get done; however it does mean the driver has to be
> > in a condition to process the last sync cache command.
> >
> > For the quick fix, just keep the current infrastructure and put back the
> > gdth_flush() command where it can be effective.
> >
> > James
> >
> >
> Totally untested.
>
> ---
> From: Boaz Harrosh <bharrosh@...asas.com>
> Subject: [PATCH] gdth: bugfix for the at-exit problems
>
> gdth_exit would first remove all cards then stop the timer
> and would not sync with the timer function. This caused a crash
> in gdth_timer() when module was unloaded.
> So del_timer_sync the timer before we delete the cards.
>
> also the reboot notifier function would crash. So unify
> the exit and halt functions with a gdth_shutdown() that's
> called by both.
>
> Signed-off-by: Boaz Harrosh <bharrosh@...asas.com>
> ---
> drivers/scsi/gdth.c | 99 ++++++++++++++++++++------------------------------
> 1 files changed, 40 insertions(+), 59 deletions(-)
>
> diff --git a/drivers/scsi/gdth.c b/drivers/scsi/gdth.c
> index 8eb78be..7bb9b45 100644
> --- a/drivers/scsi/gdth.c
> +++ b/drivers/scsi/gdth.c
> @@ -183,7 +183,6 @@ static int gdth_ioctl(struct inode *inode, struct file *filep,
> unsigned int cmd, unsigned long arg);
>
> static void gdth_flush(gdth_ha_str *ha);
> -static int gdth_halt(struct notifier_block *nb, ulong event, void *buf);
> static int gdth_queuecommand(Scsi_Cmnd *scp,void (*done)(Scsi_Cmnd *));
> static int __gdth_queuecommand(gdth_ha_str *ha, struct scsi_cmnd *scp,
> struct gdth_cmndinfo *cmndinfo);
> @@ -418,12 +417,6 @@ static inline void gdth_set_sglist(struct scsi_cmnd *cmd,
> #include "gdth_proc.h"
> #include "gdth_proc.c"
>
> -/* notifier block to get a notify on system shutdown/halt/reboot */
> -static struct notifier_block gdth_notifier = {
> - gdth_halt, NULL, 0
> -};
> -static int notifier_disabled = 0;
> -
> static gdth_ha_str *gdth_find_ha(int hanum)
> {
> gdth_ha_str *ha;
> @@ -3793,6 +3786,8 @@ static void gdth_timeout(ulong data)
> gdth_ha_str *ha;
> ulong flags;
>
> + BUG_ON(list_empty(&gdth_instances));
> +
> ha = list_first_entry(&gdth_instances, gdth_ha_str, list);
> spin_lock_irqsave(&ha->smp_lock, flags);
>
> @@ -4668,45 +4663,6 @@ static void gdth_flush(gdth_ha_str *ha)
> }
> }
>
> -/* shutdown routine */
> -static int gdth_halt(struct notifier_block *nb, ulong event, void *buf)
> -{
> - gdth_ha_str *ha;
> -#ifndef __alpha__
> - gdth_cmd_str gdtcmd;
> - char cmnd[MAX_COMMAND_SIZE];
> -#endif
> -
> - if (notifier_disabled)
> - return NOTIFY_OK;
> -
> - TRACE2(("gdth_halt() event %d\n",(int)event));
> - if (event != SYS_RESTART && event != SYS_HALT && event != SYS_POWER_OFF)
> - return NOTIFY_DONE;
> -
> - notifier_disabled = 1;
> - printk("GDT-HA: Flushing all host drives .. ");
> - list_for_each_entry(ha, &gdth_instances, list) {
> - gdth_flush(ha);
> -
> -#ifndef __alpha__
> - /* controller reset */
> - memset(cmnd, 0xff, MAX_COMMAND_SIZE);
> - gdtcmd.BoardNode = LOCALBOARD;
> - gdtcmd.Service = CACHESERVICE;
> - gdtcmd.OpCode = GDT_RESET;
> - TRACE2(("gdth_halt(): reset controller %d\n", ha->hanum));
> - gdth_execute(ha->shost, &gdtcmd, cmnd, 10, NULL);
> -#endif
> - }
> - printk("Done.\n");
> -
> -#ifdef GDTH_STATISTICS
> - del_timer(&gdth_timer);
> -#endif
> - return NOTIFY_OK;
> -}
> -
> /* configure lun */
> static int gdth_slave_configure(struct scsi_device *sdev)
> {
> @@ -5141,13 +5097,13 @@ static void gdth_remove_one(gdth_ha_str *ha)
>
> scsi_remove_host(shp);
>
> + gdth_flush(ha);
> +
> if (ha->sdev) {
> scsi_free_host_dev(ha->sdev);
> ha->sdev = NULL;
> }
>
> - gdth_flush(ha);
> -
> if (shp->irq)
> free_irq(shp->irq,ha);
>
> @@ -5173,6 +5129,40 @@ static void gdth_remove_one(gdth_ha_str *ha)
> scsi_host_put(shp);
> }
>
> +static void gdth_shutdown(void);
> +static int gdth_halt(struct notifier_block *nb, ulong event, void *buf)
> +{
> + TRACE2(("gdth_halt() event %d\n",(int)event));
> + if (event != SYS_RESTART && event != SYS_HALT && event != SYS_POWER_OFF)
> + return NOTIFY_DONE;
> +
> + gdth_shutdown();
> + return NOTIFY_OK;
> +}
> +
> +static struct notifier_block gdth_notifier = {
> + gdth_halt, NULL, 0
> +};
> +
> +bool gdth_shutdown_done;
Static police alert! Just make it static and move it into
gdth_shutdown()
> +static void gdth_shutdown()
> +{
> + gdth_ha_str *ha;
> + if (gdth_shutdown_done)
> + return;
> +
> + gdth_shutdown_done = true;
> + unregister_chrdev(major,"gdth");
> + unregister_reboot_notifier(&gdth_notifier);
I'm not sure you can do this, aren't reboot notifiers called with the
rwsem held? In which case the unregister which also takes the rwsem
will hang the system.
James
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