[PATCH AUTOSEL 4.19 022/237] cdrom: don't attempt to fiddle with cdo->capability

Sasha Levin
2019-11-16T16:27:35Z

From: Jens Axboe <axboe@kernel.dk>

[ Upstream commit 8f94004e2a51a3ea195cf3447eb5d5906f36d8b3 ]

We can't modify cdo->capability as it is defined as a const.
Change the modification hack to just WARN_ON_ONCE() if we hit
any of the invalid combinations.

This fixes a regression for pcd, which doesn't work after the
constify patch.

Fixes: 853fe1bf7554 ("cdrom: Make device operations read-only")
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/cdrom/cdrom.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 27a82a559ab94..933268b8d6a54 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -411,10 +411,10 @@ static int cdrom_get_disc_info(struct cdrom_device_info *cdi,
* hack to have the capability flags defined const, while we can still
* change it here without gcc complaining at every line.
*/
-#define ENSURE(call, bits) \
-do { \
- if (cdo->call == NULL) \
- *change_capability &= ~(bits); \
+#define ENSURE(cdo, call, bits) \
+do { \
+ if (cdo->call == NULL) \
+ WARN_ON_ONCE((cdo)->capability & (bits)); \
} while (0)

/*
@@ -590,7 +590,6 @@ int register_cdrom(struct cdrom_device_info *cdi)
{
static char banner_printed;
const struct cdrom_device_ops *cdo = cdi->ops;
- int *change_capability = (int *)&cdo->capability; /* hack */

cd_dbg(CD_OPEN, "entering register_cdrom\n");

@@ -602,16 +601,16 @@ int register_cdrom(struct cdrom_device_info *cdi)
cdrom_sysctl_register();
}

- ENSURE(drive_status, CDC_DRIVE_STATUS);
+ ENSURE(cdo, drive_status, CDC_DRIVE_STATUS);
if (cdo->check_events == NULL && cdo->media_changed == NULL)
- *change_capability = ~(CDC_MEDIA_CHANGED | CDC_SELECT_DISC);
- ENSURE(tray_move, CDC_CLOSE_TRAY | CDC_OPEN_TRAY);
- ENSURE(lock_door, CDC_LOCK);
- ENSURE(select_speed, CDC_SELECT_SPEED);
- ENSURE(get_last_session, CDC_MULTI_SESSION);
- ENSURE(get_mcn, CDC_MCN);
- ENSURE(reset, CDC_RESET);
- ENSURE(generic_packet, CDC_GENERIC_PACKET);
+ WARN_ON_ONCE(cdo->capability & (CDC_MEDIA_CHANGED | CDC_SELECT_DISC));
+ ENSURE(cdo, tray_move, CDC_CLOSE_TRAY | CDC_OPEN_TRAY);
+ ENSURE(cdo, lock_door, CDC_LOCK);
+ ENSURE(cdo, select_speed, CDC_SELECT_SPEED);
+ ENSURE(cdo, get_last_session, CDC_MULTI_SESSION);
+ ENSURE(cdo, get_mcn, CDC_MCN);
+ ENSURE(cdo, reset, CDC_RESET);
+ ENSURE(cdo, generic_packet, CDC_GENERIC_PACKET);
cdi->mc_flags = 0;
cdi->options = CDO_USE_FFLAGS;

--
2.20.1