linux-kernel - [PATCH 8/8] lib/zlib: DFLTCC always switch to software inflate for Z_PACKET

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Date:   Thu, 26 Jan 2023 14:14:28 +0100
From:   Mikhail Zaslonko <zaslonko@...ux.ibm.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Mikhail Zaslonko <zaslonko@...ux.ibm.com>
Subject: [PATCH 8/8] lib/zlib: DFLTCC always switch to software inflate for Z_PACKET_FLUSH option

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.

Signed-off-by: Mikhail Zaslonko <zaslonko@...ux.ibm.com>
Acked-by: Ilya Leoshkevich <iii@...ux.ibm.com>
---
 lib/zlib_dfltcc/dfltcc_inflate.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/zlib_dfltcc/dfltcc_inflate.c b/lib/zlib_dfltcc/dfltcc_inflate.c
index 5786030c6dc2..437cd34c8490 100644
--- a/lib/zlib_dfltcc/dfltcc_inflate.c
+++ b/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;
-- 
2.34.1