linux-kernel - Re: [PATCH 0/3] firewire: core: serialize topology building and bus manager work

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Message-ID: <20250917124208.GA56969@workstation.local>
Date: Wed, 17 Sep 2025 21:42:08 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] firewire: core: serialize topology building and bus
 manager work

On Wed, Sep 17, 2025 at 09:03:44AM +0900, Takashi Sakamoto wrote:
> Hi,
> 
> Two functions, fw_core_handle_bus_reset() and bm_work(), acquire fw_card
> spin lock, however each purpose is different.  The former function manages
> to update some members of fw_card, and the latter function manages just to
> access these members of fw_card. This reflects that the members are valid
> during current bus generation once determined by the former function.
> 
> Current implementation schedules a work item for the latter function under
> acquiring the spin lock in the former function. This could causes the
> latter function to be stalled by spinning until the former function
> finishes, depending on the timing to invoke the work item.
> 
> This patchset suppresses the stalling by serializing these two
> functions. In former commits, the former function is invoked by IRQ
> thread, thus sleep-able. The former function disables the work item
> synchronously, then acquires the spin lock to update the members of
> fw_card. After that, it releases the spin lock, then enable and schedule
> the work item. The latter function is free from the spin lock.
> 
> Takashi Sakamoto (3):
>   firewire: core: schedule bm_work item outside of spin lock
>   firewire: core: disable bus management work temporarily during
>     updating topology
>   firewire: core: shrink critical section of fw_card spinlock in bm_work
> 
>  drivers/firewire/core-card.c     | 30 ++++++++----------------------
>  drivers/firewire/core-topology.c | 11 ++++++++++-
>  2 files changed, 18 insertions(+), 23 deletions(-)

Applied to for-next branch.


Regards

Takashi Sakamoto