From: Daniel Axtens <dja@axtens•net>
To: Jordan Niethe <jniethe5@gmail•com>,
linuxppc-dev@lists•ozlabs.org, christophe.leroy@csgroup•eu
Cc: Jordan Niethe <jniethe5@gmail•com>,
npiggin@gmail•com, aneesh.kumar@linux•ibm.com
Subject: Re: [PATCH 2/4] powerpc/64s: Remove unneeded #ifdef CONFIG_DEBUG_PAGEALLOC in hash_utils
Date: Fri, 18 Jun 2021 17:49:04 +1000 [thread overview]
Message-ID: <87eeczsjdb.fsf@dja-thinkpad.axtens.net> (raw)
In-Reply-To: <20210517061658.194708-3-jniethe5@gmail.com>
Hi Jordan and Christophe,
> --- a/arch/powerpc/mm/book3s64/hash_utils.c
> +++ b/arch/powerpc/mm/book3s64/hash_utils.c
> @@ -126,11 +126,8 @@ EXPORT_SYMBOL_GPL(mmu_slb_size);
> #ifdef CONFIG_PPC_64K_PAGES
> int mmu_ci_restrictions;
> #endif
> -#ifdef CONFIG_DEBUG_PAGEALLOC
> static u8 *linear_map_hash_slots;
> static unsigned long linear_map_hash_count;
> -static DEFINE_SPINLOCK(linear_map_hash_lock);
> -#endif /* CONFIG_DEBUG_PAGEALLOC */
> struct mmu_hash_ops mmu_hash_ops;
> EXPORT_SYMBOL(mmu_hash_ops);
>
> @@ -1944,6 +1937,8 @@ long hpte_insert_repeating(unsigned long hash, unsigned long vpn,
> }
>
> #ifdef CONFIG_DEBUG_PAGEALLOC
> +static DEFINE_SPINLOCK(linear_map_hash_lock);
> +
I had some trouble figuring out why the spinlock has to be in the
ifdef. A bit of investigation suggests that it's only used in functions
that are only defined under CONFIG_DEBUG_PAGEALLOC - unlike the other
variables. So that makes sense.
While I was poking around, I noticed that linear_map_hash_slots is
manipulated under linear_map_hash_lock in kernel_(un)map_linear_page but
is manipulated outside the lock in htab_bolt_mapping(). Is that OK? (I
don't know when htab_bolt_mapping is called, it's possible it's only
called at times where nothing else could be happing to that array.)
Kind regards,
Daniel
> static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
> {
> unsigned long hash;
> --
> 2.25.1
next prev parent reply other threads:[~2021-06-18 7:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 6:16 [PATCH 0/4] powerpc/64s: Enable KFENCE Jordan Niethe
2021-05-17 6:16 ` [PATCH 1/4] powerpc/64s: Add DEBUG_PAGEALLOC for radix Jordan Niethe
2021-06-18 7:28 ` Daniel Axtens
2021-05-17 6:16 ` [PATCH 2/4] powerpc/64s: Remove unneeded #ifdef CONFIG_DEBUG_PAGEALLOC in hash_utils Jordan Niethe
2021-06-18 7:49 ` Daniel Axtens [this message]
2021-05-17 6:16 ` [PATCH 3/4] powerpc/64s: Allow double call of kernel_[un]map_linear_page() Jordan Niethe
2021-05-17 6:16 ` [PATCH 4/4] powerpc: Enable KFENCE on BOOK3S/64 Jordan Niethe
2021-06-18 8:00 ` Daniel Axtens
2021-06-18 8:02 ` Daniel Axtens
2021-06-22 8:57 ` Michael Ellerman
-- strict thread matches above, loose matches on Subject: below --
2022-09-19 1:44 [PATCH 1/4] powerpc/64s: Add DEBUG_PAGEALLOC for radix Nicholas Miehlbradt
2022-09-19 1:44 ` [PATCH 2/4] powerpc/64s: Remove unneeded #ifdef CONFIG_DEBUG_PAGEALLOC in hash_utils Nicholas Miehlbradt
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