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Bottomley" , Helge Deller , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Minchan Kim , Sergey Senozhatsky , Jens Axboe , Andrew Morton , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-s390@vger.kernel.org, linux-block@vger.kernel.org, Yann Collet , Nick Terrell , Gao Xiang , Chao Yu , Jaegeuk Kim , Herbert Xu , Phillip Lougher , Sungguk , Jaehoon Chung , Marek Szyprowski , linux-erofs@lists.ozlabs.org, linux-f2fs-devel@lists.sourceforge.net, linux-crypto@vger.kernel.org Subject: Re: [PATCH RFC 1/9] lib/lz4: import upstream LZ4 sources verbatim Message-ID: References: <20260925-lz4-vendor-upstream-v1-0-1c7ffbe21c4b@samsung.com> <20260925-lz4-vendor-upstream-v1-1-1c7ffbe21c4b@samsung.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260925-lz4-vendor-upstream-v1-1-1c7ffbe21c4b@samsung.com> On (26/09/25 13:27), Michal Wilczynski wrote: [..] > +void LZ4_resetStream_fast(LZ4_stream_t* ctx) { > + LZ4_prepareTable(&(ctx->internal_donotuse), 0, byU32); > +} [..] > +void LZ4_attach_dictionary(LZ4_stream_t* workingStream, const LZ4_stream_t* dictionaryStream) > +{ > + const LZ4_stream_t_internal* dictCtx = (dictionaryStream == NULL) ? NULL : > + &(dictionaryStream->internal_donotuse); > + > + DEBUGLOG(4, "LZ4_attach_dictionary (%p, %p, size %u)", > + workingStream, dictionaryStream, > + dictCtx != NULL ? dictCtx->dictSize : 0); > + > + if (dictCtx != NULL) { > + /* If the current offset is zero, we will never look in the > + * external dictionary context, since there is no value a table > + * entry can take that indicate a miss. In that case, we need > + * to bump the offset to something non-zero. > + */ > + if (workingStream->internal_donotuse.currentOffset == 0) { > + workingStream->internal_donotuse.currentOffset = 64 KB; > + } > + > + /* Don't actually attach an empty dictionary. > + */ > + if (dictCtx->dictSize == 0) { > + dictCtx = NULL; > + } > + } > + workingStream->internal_donotuse.dictCtx = dictCtx; > +} Just a side note, there is a bunch of new helpful API added in this release. Currently, we do some memcpy hacks to avoid re-init of lz4 C/D-dict in zram, but once this series lands I'll be happy to send some trivial EXPORT_SYMBOL patches so that zram (and other lz4 users) can use standard lz4 dict API instead of hacks.