+ lib-zlib-implement-switching-between-dfltcc-and-software.patch added to mm-nonmm-unstable branch

+ lib-zlib-implement-switching-between-dfltcc-and-software.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: lib/zlib: implement switching between DFLTCC and software
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     lib-zlib-implement-switching-between-dfltcc-and-software.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-zlib-implement-switching-between-dfltcc-and-software.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Subject: lib/zlib: implement switching between DFLTCC and software
Date: Thu, 26 Jan 2023 14:14:22 +0100

This commit is based on:
  https://github.com/zlib-ng/zlib-ng/commit/fc04275

Link: https://lkml.kernel.org/r/20230126131428.1222214-3-zaslonko@linux.ibm.com
Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/zlib_dfltcc/dfltcc_deflate.c |   38 ++++++++++++++++-------------
 1 file changed, 22 insertions(+), 16 deletions(-)

--- a/lib/zlib_dfltcc/dfltcc_deflate.c~lib-zlib-implement-switching-between-dfltcc-and-software
+++ a/lib/zlib_dfltcc/dfltcc_deflate.c
@@ -112,30 +112,36 @@ int dfltcc_deflate(
     int soft_bcc;
     int no_flush;
 
-    if (!dfltcc_can_deflate(strm))
+    if (!dfltcc_can_deflate(strm)) {
+        /* Clear history. */
+        if (flush == Z_FULL_FLUSH)
+            param->hl = 0;
         return 0;
+    }
 
 again:
     masked_avail_in = 0;
     soft_bcc = 0;
     no_flush = flush == Z_NO_FLUSH;
 
-    /* Trailing empty block. Switch to software, except when Continuation Flag
-     * is set, which means that DFLTCC has buffered some output in the
-     * parameter block and needs to be called again in order to flush it.
+    /* No input data. Return, except when Continuation Flag is set, which means
+     * that DFLTCC has buffered some output in the parameter block and needs to
+     * be called again in order to flush it.
      */
-    if (flush == Z_FINISH && strm->avail_in == 0 && !param->cf) {
-        if (param->bcf) {
-            /* A block is still open, and the hardware does not support closing
-             * blocks without adding data. Thus, close it manually.
-             */
+    if (strm->avail_in == 0 && !param->cf) {
+        /* A block is still open, and the hardware does not support closing
+         * blocks without adding data. Thus, close it manually.
+         */
+        if (!no_flush && param->bcf) {
             send_eobs(strm, param);
             param->bcf = 0;
         }
-        return 0;
-    }
-
-    if (strm->avail_in == 0 && !param->cf) {
+        /* Let one of deflate_* functions write a trailing empty block. */
+        if (flush == Z_FINISH)
+            return 0;
+        /* Clear history. */
+        if (flush == Z_FULL_FLUSH)
+            param->hl = 0;
         *result = need_more;
         return 1;
     }
@@ -189,7 +195,7 @@ again:
     param->cvt = CVT_ADLER32;
     if (!no_flush)
         /* We need to close a block. Always do this in software - when there is
-         * no input data, the hardware will not nohor BCC. */
+         * no input data, the hardware will not hohor BCC. */
         soft_bcc = 1;
     if (flush == Z_FINISH && !param->bcf)
         /* We are about to open a BFINAL block, set Block Header Final bit
@@ -204,8 +210,8 @@ again:
     param->sbb = (unsigned int)state->bi_valid;
     if (param->sbb > 0)
         *strm->next_out = (Byte)state->bi_buf;
-    if (param->hl)
-        param->nt = 0; /* Honor history */
+    /* Honor history and check value */
+    param->nt = 0;
     param->cv = strm->adler;
 
     /* When opening a block, choose a Huffman-Table Type */
_

Patches currently in -mm which might be from zaslonko@linux.ibm.com are

lib-zlib-adjust-offset-calculation-for-dfltcc_state.patch
lib-zlib-implement-switching-between-dfltcc-and-software.patch
lib-zlib-fix-dfltcc-not-flushing-eobs-when-creating-raw-streams.patch
lib-zlib-fix-dfltcc-ignoring-flush-modes-when-avail_in-==-0.patch
lib-zlib-dfltcc-not-writing-header-bits-when-avail_out-==-0.patch
lib-zlib-split-deflate-and-inflate-states-for-dfltcc.patch
lib-zlib-dfltcc-support-inflate-with-small-window.patch
lib-zlib-dfltcc-always-switch-to-software-inflate-for-z_packet_flush-option.patch