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media: i2c: ds90ub960: Protect alias_use_mask with a mutex

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The aliased_addrs list represents the occupation of an RX port's hardware
alias table. This list and the underlying hardware table are only accessed
in the attach/detach_client() callbacks.

These functions are only called from a bus notifier handler in i2c-atr.c,
which is always called with the notifier chain's semaphore held. This
indirectly prevents concurrent access to the aliased_addrs list.
However, more explicit and direct locking is preferable. Moreover, with the
introduction of dynamic address translation in a future patch, the
attach/detach_client() callbacks will be called from outside of the
notifier chain's read section.

Introduce a mutex to protect access to the aliased_addrs list and its
underlying hardware table.

Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>
Acked-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
This commit is contained in:
Romain Gantois
2025-03-06 17:23:24 +01:00
committed by Wolfram Sang
parent 666be28145
commit 3ec29d51b5
1 changed files with 11 additions and 0 deletions
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11
drivers/media/i2c/ds90ub960.c
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@@ -27,6 +27,7 @@
*/
#include <linux/bitops.h>
#include <linux/cleanup.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/fwnode.h>
@@ -478,6 +479,8 @@ struct ub960_rxport {
};
} eq;
/* lock for aliased_addrs and associated registers */
struct mutex aliased_addrs_lock;
u16 aliased_addrs[UB960_MAX_PORT_ALIASES];
};
@@ -1054,6 +1057,8 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id,
struct device *dev = &priv->client->dev;
unsigned int reg_idx;
guard(mutex)(&rxport->aliased_addrs_lock);
for (reg_idx = 0; reg_idx < ARRAY_SIZE(rxport->aliased_addrs); reg_idx++) {
if (!rxport->aliased_addrs[reg_idx])
break;
@@ -1085,6 +1090,8 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id,
struct device *dev = &priv->client->dev;
unsigned int reg_idx;
guard(mutex)(&rxport->aliased_addrs_lock);
for (reg_idx = 0; reg_idx < ARRAY_SIZE(rxport->aliased_addrs); reg_idx++) {
if (rxport->aliased_addrs[reg_idx] == client->addr)
break;
@@ -3235,6 +3242,8 @@ static void ub960_rxport_free_ports(struct ub960_data *priv)
fwnode_handle_put(rxport->source.ep_fwnode);
fwnode_handle_put(rxport->ser.fwnode);
mutex_destroy(&rxport->aliased_addrs_lock);
kfree(rxport);
priv->rxports[nport] = NULL;
}
@@ -3455,6 +3464,8 @@ static int ub960_parse_dt_rxport(struct ub960_data *priv, unsigned int nport,
if (ret)
goto err_put_remote_fwnode;
mutex_init(&rxport->aliased_addrs_lock);
return 0;
err_put_remote_fwnode: