linux-kernel - Re: [PATCH] hpsa: fix boot on ia64 (atomic

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Message-ID: <yq1zgz21rkz.fsf@ca-mkp.ca.oracle.com>
Date:   Tue, 16 Mar 2021 22:25:30 -0400
From:   "Martin K. Petersen" <martin.petersen@...cle.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Don.Brace@...rochip.com, Sergei Trofimovich <slyfox@...too.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-ia64@...r.kernel.org, storagedev@...rochip.com,
        linux-scsi <linux-scsi@...r.kernel.org>, jszczype@...hat.com,
        Scott.Benesh@...rochip.com, Scott.Teel@...rochip.com,
        thenzl@...hat.com,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Subject: Re: [PATCH] hpsa: fix boot on ia64 (atomic_t alignment)


Arnd,

> Actually that still feels wrong: the annotation of the struct is to
> pack every member, which causes the access to be done in byte units on
> architectures that do not have hardware unaligned load/store
> instructions, at least for things like atomic_read() that does not go
> through a cmpxchg() or ll/sc cycle.

> This change may fix itanium, but it's still not correct. Other
> architectures would have already been broken before the recent change,
> but that's not a reason against fixing them now.

I agree. I understand why there are restrictions on fields consumed by
the hardware. But for fields internal to the driver the packing doesn't
make sense to me.

-- 
Martin K. Petersen	Oracle Linux Engineering