linux-kernel - [PATCH 6/6] s390: simplify dynamic sysctl registration for appldata_register

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Message-Id: <20230310234525.3986352-7-mcgrof@kernel.org>
Date:   Fri, 10 Mar 2023 15:45:25 -0800
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     hca@...ux.ibm.com, agordeev@...ux.ibm.com,
        borntraeger@...ux.ibm.com, svens@...ux.ibm.com,
        linux-s390@...r.kernel.org, sudipm.mukherjee@...il.com
Cc:     ebiederm@...ssion.com, keescook@...omium.org, yzaikin@...gle.com,
        j.granados@...sung.com, patches@...ts.linux.dev,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Luis Chamberlain <mcgrof@...nel.org>
Subject: [PATCH 6/6] s390: simplify dynamic sysctl registration for appldata_register_ops

The routine appldata_register_ops() allocates a sysctl table
with 4 entries. The firsts one,   ops->ctl_table[0] is the parent directory
with an empty entry following it, ops->ctl_table[1]. The next entry is
for the the ops->name and that is ops->ctl_table[2]. It needs an empty
entry following that, and that is ops->ctl_table[3]. And so hence the
kcalloc(4, sizeof(struct ctl_table), GFP_KERNEL).

We can simplify this considerably since sysctl_register("foo", table)
can create the parent directory for us if it does not exist. So we
can just remove the first two entries and move back the ops->name to
the first entry, and just use kcalloc(2, ...).

Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 arch/s390/appldata/appldata_base.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/s390/appldata/appldata_base.c b/arch/s390/appldata/appldata_base.c
index c593f2228083..a60c1e093039 100644
--- a/arch/s390/appldata/appldata_base.c
+++ b/arch/s390/appldata/appldata_base.c
@@ -351,7 +351,8 @@ int appldata_register_ops(struct appldata_ops *ops)
 	if (ops->size > APPLDATA_MAX_REC_SIZE)
 		return -EINVAL;
 
-	ops->ctl_table = kcalloc(4, sizeof(struct ctl_table), GFP_KERNEL);
+	/* The last entry must be an empty one */
+	ops->ctl_table = kcalloc(2, sizeof(struct ctl_table), GFP_KERNEL);
 	if (!ops->ctl_table)
 		return -ENOMEM;
 
@@ -359,17 +360,12 @@ int appldata_register_ops(struct appldata_ops *ops)
 	list_add(&ops->list, &appldata_ops_list);
 	mutex_unlock(&appldata_ops_mutex);
 
-	ops->ctl_table[0].procname = appldata_proc_name;
-	ops->ctl_table[0].maxlen   = 0;
-	ops->ctl_table[0].mode     = S_IRUGO | S_IXUGO;
-	ops->ctl_table[0].child    = &ops->ctl_table[2];
+	ops->ctl_table[0].procname = ops->name;
+	ops->ctl_table[0].mode     = S_IRUGO | S_IWUSR;
+	ops->ctl_table[0].proc_handler = appldata_generic_handler;
+	ops->ctl_table[0].data = ops;
 
-	ops->ctl_table[2].procname = ops->name;
-	ops->ctl_table[2].mode     = S_IRUGO | S_IWUSR;
-	ops->ctl_table[2].proc_handler = appldata_generic_handler;
-	ops->ctl_table[2].data = ops;
-
-	ops->sysctl_header = register_sysctl_table(ops->ctl_table);
+	ops->sysctl_header = register_sysctl(appldata_proc_name, ops->ctl_table);
 	if (!ops->sysctl_header)
 		goto out;
 	return 0;
-- 
2.39.1