+ lib-zlib-dfltcc-always-switch-to-software-inflate-for-z_packet_flush-option.patch added to mm-nonmm-unstable branch

+ lib-zlib-dfltcc-always-switch-to-software-inflate-for-z_packet_flush-option.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: lib/zlib: DFLTCC always switch to software inflate for Z_PACKET_FLUSH option
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     lib-zlib-dfltcc-always-switch-to-software-inflate-for-z_packet_flush-option.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-zlib-dfltcc-always-switch-to-software-inflate-for-z_packet_flush-option.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: DFLTCC always switch to software inflate for Z_PACKET_FLUSH option
Date: Thu, 26 Jan 2023 14:14:28 +0100

Since hardware inflate does not support Z_PACKET_FLUSH option (used
exclusively by kernel PPP driver), always switch to software like we
already do for Z_BLOCK flush option.  Without this patch, PPP might get
Z_DATA_ERROR return code from zlib_inflate() and disable zlib compression
for the packets.

Link: https://lkml.kernel.org/r/20230126131428.1222214-9-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_inflate.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/lib/zlib_dfltcc/dfltcc_inflate.c~lib-zlib-dfltcc-always-switch-to-software-inflate-for-z_packet_flush-option
+++ a/lib/zlib_dfltcc/dfltcc_inflate.c
@@ -95,8 +95,10 @@ dfltcc_inflate_action dfltcc_inflate(
     struct dfltcc_param_v0 *param = &dfltcc_state->param;
     dfltcc_cc cc;
 
-    if (flush == Z_BLOCK) {
-        /* DFLTCC does not support stopping on block boundaries */
+    if (flush == Z_BLOCK || flush == Z_PACKET_FLUSH) {
+        /* DFLTCC does not support stopping on block boundaries (Z_BLOCK flush option)
+         * as well as the use of Z_PACKET_FLUSH option (used exclusively by PPP driver)
+         */
         if (dfltcc_inflate_disable(strm)) {
             *ret = Z_STREAM_ERROR;
             return DFLTCC_INFLATE_BREAK;
_

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