grub2/0164-make-ofdisk_retries-optional.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Diego Domingos <diegdo@br.ibm.com>
Date: Thu, 24 Mar 2022 13:14:42 -0400
Subject: [PATCH] make ofdisk_retries optional

The feature Retry on Fail added to GRUB can cause a LPM to take
longer if the SAN is slow.

When a LPM to external site occur, the path of the disk can change
and thus the disk search function on grub can take some time since
it is used as a hint. This can cause the Retry on Fail feature to
try to access the disk 20x times (since this is hardcoded number)
and, if the SAN is slow, the boot time can increase a lot.
In some situations not acceptable.

The following patch enables a configuration at user space of the
maximum number of retries we want for this feature.

The variable ofdisk_retries should be set using grub2-editenv
and will be checked by retry function. If the variable is not set,
so the default number of retries will be used instead.
---
 include/grub/ieee1275/ofdisk.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/grub/ieee1275/ofdisk.h b/include/grub/ieee1275/ofdisk.h
index 7d2d5409305..0074d55eee4 100644
--- a/include/grub/ieee1275/ofdisk.h
+++ b/include/grub/ieee1275/ofdisk.h
@@ -25,7 +25,12 @@ extern void grub_ofdisk_fini (void);
 #define MAX_RETRIES 20
 
 
-#define RETRY_IEEE1275_OFDISK_OPEN(device, last_ihandle) unsigned retry_i=0;for(retry_i=0; retry_i < MAX_RETRIES; retry_i++){ \
+#define RETRY_IEEE1275_OFDISK_OPEN(device, last_ihandle) \
+	                                        unsigned max_retries = MAX_RETRIES; \
+                                                if(grub_env_get("ofdisk_retries") != NULL) \
+                                                     max_retries = grub_strtoul(grub_env_get("ofdisk_retries"), 0, 10)+1; \
+                                                grub_dprintf("ofdisk","MAX_RETRIES set to %u\n",max_retries); \
+                                                unsigned retry_i=0;for(retry_i=0; retry_i < max_retries; retry_i++){ \
 						if(!grub_ieee1275_open(device, last_ihandle)) \
 						break; \
 						grub_dprintf("ofdisk","Opening disk %s failed. Retrying...\n",device); }