[PATCH] lib/xxhash: Comment out unused functions

[PATCH] lib/xxhash: Comment out unused functions

[linux]

From: "Dr. David Alan Gilbert" <linux@treblig.org>

xxh32_digest() and xxh32_update() were added in 2017 in the original
xxhash commit, but have remained unused.

While I've mostly been deleting unused functions, this is a general
library and I see erofs is using other bits of xxh32, so it didn't
seem right just to delete them.

Comment them out with #if 0.
(Which checkpatch rightly warns about)

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
---
 include/linux/xxhash.h | 4 ++++
 lib/xxhash.c           | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/include/linux/xxhash.h b/include/linux/xxhash.h
index df42511438d0..46d513a0212a 100644
--- a/include/linux/xxhash.h
+++ b/include/linux/xxhash.h
@@ -177,6 +177,9 @@ struct xxh64_state {
  */
 void xxh32_reset(struct xxh32_state *state, uint32_t seed);
 
+#if 0
+/* Currently unused, feel free to uncomment them if you use them. */
+
 /**
  * xxh32_update() - hash the data given and update the xxh32 state
  *
@@ -202,6 +205,7 @@ int xxh32_update(struct xxh32_state *state, const void *input, size_t length);
  * Return: The xxh32 hash stored in the state.
  */
 uint32_t xxh32_digest(const struct xxh32_state *state);
+#endif
 
 /**
  * xxh64_reset() - reset the xxh64 state to start a new hashing operation
diff --git a/lib/xxhash.c b/lib/xxhash.c
index b5bd567aa6b3..988a22e9a139 100644
--- a/lib/xxhash.c
+++ b/lib/xxhash.c
@@ -267,6 +267,7 @@ void xxh64_reset(struct xxh64_state *statePtr, const uint64_t seed)
 }
 EXPORT_SYMBOL(xxh64_reset);
 
+#if 0
 int xxh32_update(struct xxh32_state *state, const void *input, const size_t len)
 {
 	const uint8_t *p = (const uint8_t *)input;
@@ -373,6 +374,7 @@ uint32_t xxh32_digest(const struct xxh32_state *state)
 	return h32;
 }
 EXPORT_SYMBOL(xxh32_digest);
+#endif
 
 int xxh64_update(struct xxh64_state *state, const void *input, const size_t len)
 {
-- 
2.50.1

Re: [PATCH] lib/xxhash: Comment out unused functions

[Christoph Hellwig]

On Mon, Jul 14, 2025 at 01:09:27AM +0100, linux@treblig.org wrote:
> From: "Dr. David Alan Gilbert" <linux@treblig.org>
> 
> xxh32_digest() and xxh32_update() were added in 2017 in the original
> xxhash commit, but have remained unused.
> 
> While I've mostly been deleting unused functions, this is a general
> library and I see erofs is using other bits of xxh32, so it didn't
> seem right just to delete them.
> 
> Comment them out with #if 0.
> (Which checkpatch rightly warns about)

Please just remove it like all other dead code.  The same argument
that folks can easily look at the git history to resurrect it applies
here as everywhere else.

Re: [PATCH] lib/xxhash: Comment out unused functions

[Dr. David Alan Gilbert]

* Christoph Hellwig (hch@infradead.org) wrote:
> On Mon, Jul 14, 2025 at 01:09:27AM +0100, linux@treblig.org wrote:
> > From: "Dr. David Alan Gilbert" <linux@treblig.org>
> > 
> > xxh32_digest() and xxh32_update() were added in 2017 in the original
> > xxhash commit, but have remained unused.
> > 
> > While I've mostly been deleting unused functions, this is a general
> > library and I see erofs is using other bits of xxh32, so it didn't
> > seem right just to delete them.
> > 
> > Comment them out with #if 0.
> > (Which checkpatch rightly warns about)
> 
> Please just remove it like all other dead code.  The same argument
> that folks can easily look at the git history to resurrect it applies
> here as everywhere else.

Hmm OK, as requested, v2 posted:

Subject: [PATCH v2] lib/xxhash: Remove unused functions
Date: Wed, 16 Jul 2025 14:32:45 +0100
Message-ID: <20250716133245.243363-1-linux@treblig.org>

Dave
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