linux-kernel - [PATCH] vmci_host: print unexpanded names of ioctl requests in debug messages

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Message-Id: <20210302153346.300416-1-glebfm@altlinux.org>
Date:   Tue,  2 Mar 2021 18:33:46 +0300
From:   Gleb Fotengauer-Malinovskiy <glebfm@...linux.org>
To:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Souptick Joarder <jrdr.linux@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>
Cc:     Gleb Fotengauer-Malinovskiy <glebfm@...linux.org>,
        linux-kernel@...r.kernel.org, Vitaly Chikunov <vt@...linux.org>
Subject: [PATCH] vmci_host: print unexpanded names of ioctl requests in debug messages

__stringify macro function expands its arguments, but in this messages
we expect to see ioctl request name instead of it's _IOC macro
expansion.

$ cat stringify.c

#include <stdio.h>
#include <asm/ioctl.h>

#define __stringify_1(x)	#x
#define __stringify(x)		__stringify_1(x)

#define VMCI_DO_IOCTL(ioctl_name) \
    char *name = __stringify(IOCTL_VMCI_ ## ioctl_name);

int main() {
        VMCI_DO_IOCTL(INIT_CONTEXT)
        printf("%s\n", name);
}
$ cc stringify.c
$ ./a.out
(((0U) << (((0+8)+8)+14)) | (((7)) << (0+8)) | (((0xa0)) << 0) | ((0) << ((0+8)+8)))

Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@...linux.org>
---
 drivers/misc/vmw_vmci/vmci_host.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/vmw_vmci/vmci_host.c b/drivers/misc/vmw_vmci/vmci_host.c
index 2d8328d928d5..da1e2a773823 100644
--- a/drivers/misc/vmw_vmci/vmci_host.c
+++ b/drivers/misc/vmw_vmci/vmci_host.c
@@ -908,7 +908,7 @@ static long vmci_host_unlocked_ioctl(struct file *filp,
 				     unsigned int iocmd, unsigned long ioarg)
 {
 #define VMCI_DO_IOCTL(ioctl_name, ioctl_fn) do {			\
-		char *name = __stringify(IOCTL_VMCI_ ## ioctl_name);	\
+		char *name = "IOCTL_VMCI_" # ioctl_name;		\
 		return vmci_host_do_ ## ioctl_fn(			\
 			vmci_host_dev, name, uptr);			\
 	} while (0)
-- 
glebfm