| Message ID | 20241230-fpc202-v4-3-761b297dc697@bootlin.com |
|---|---|
| State | New |
| Headers | show |
| Series | misc: Support TI FPC202 dual-port controller | expand |
Hi, On 30/12/2024 15:22, Romain Gantois wrote: > 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. > > Signed-off-by: Romain Gantois <romain.gantois@bootlin.com> > --- > drivers/media/i2c/ds90ub960.c | 23 ++++++++++++++++++++--- > 1 file changed, 20 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c > index 7534ddf2079fef466d3a114f0be98599427639fa..0510427ac4e9214132bcdf3fa18873ec78c48a5e 100644 > --- a/drivers/media/i2c/ds90ub960.c > +++ b/drivers/media/i2c/ds90ub960.c > @@ -467,6 +467,8 @@ struct ub960_rxport { > }; > } eq; > > + /* lock for aliased_addrs and associated registers */ > + struct mutex aliased_addrs_lock; > u16 aliased_addrs[UB960_MAX_PORT_ALIASES]; > }; > > @@ -1030,6 +1032,9 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, > struct ub960_rxport *rxport = priv->rxports[chan_id]; > struct device *dev = &priv->client->dev; > unsigned int reg_idx; > + int ret = 0; > + > + mutex_lock(&rxport->aliased_addrs_lock); A mutex guard could be used here and below. Tomi > > for (reg_idx = 0; reg_idx < UB960_MAX_PORT_ALIASES; reg_idx++) { > if (!rxport->aliased_addrs[reg_idx]) > @@ -1038,7 +1043,8 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, > > if (reg_idx == UB960_MAX_PORT_ALIASES) { > dev_err(dev, "rx%u: alias pool exhausted\n", rxport->nport); > - return -EADDRNOTAVAIL; > + ret = -EADDRNOTAVAIL; > + goto out_unlock; > } > > rxport->aliased_addrs[reg_idx] = client->addr; > @@ -1051,7 +1057,9 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, > dev_dbg(dev, "rx%u: client 0x%02x assigned alias 0x%02x at slot %u\n", > rxport->nport, client->addr, alias, reg_idx); > > - return 0; > +out_unlock: > + mutex_unlock(&rxport->aliased_addrs_lock); > + return ret; > } > > static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, > @@ -1062,6 +1070,8 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, > struct device *dev = &priv->client->dev; > unsigned int reg_idx; > > + mutex_lock(&rxport->aliased_addrs_lock); > + > for (reg_idx = 0; reg_idx < UB960_MAX_PORT_ALIASES; reg_idx++) { > if (rxport->aliased_addrs[reg_idx] == client->addr) > break; > @@ -1070,7 +1080,7 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, > if (reg_idx == UB960_MAX_PORT_ALIASES) { > dev_err(dev, "rx%u: client 0x%02x is not mapped!\n", > rxport->nport, client->addr); > - return; > + goto out_unlock; > } > > rxport->aliased_addrs[reg_idx] = 0; > @@ -1079,6 +1089,9 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, > > dev_dbg(dev, "rx%u: client 0x%02x released at slot %u\n", rxport->nport, > client->addr, reg_idx); > + > +out_unlock: > + mutex_unlock(&rxport->aliased_addrs_lock); > } > > static const struct i2c_atr_ops ub960_atr_ops = { > @@ -3181,6 +3194,8 @@ 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; > } > @@ -3401,6 +3416,8 @@ 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: >
diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c index 7534ddf2079fef466d3a114f0be98599427639fa..0510427ac4e9214132bcdf3fa18873ec78c48a5e 100644 --- a/drivers/media/i2c/ds90ub960.c +++ b/drivers/media/i2c/ds90ub960.c @@ -467,6 +467,8 @@ struct ub960_rxport { }; } eq; + /* lock for aliased_addrs and associated registers */ + struct mutex aliased_addrs_lock; u16 aliased_addrs[UB960_MAX_PORT_ALIASES]; }; @@ -1030,6 +1032,9 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, struct ub960_rxport *rxport = priv->rxports[chan_id]; struct device *dev = &priv->client->dev; unsigned int reg_idx; + int ret = 0; + + mutex_lock(&rxport->aliased_addrs_lock); for (reg_idx = 0; reg_idx < UB960_MAX_PORT_ALIASES; reg_idx++) { if (!rxport->aliased_addrs[reg_idx]) @@ -1038,7 +1043,8 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, if (reg_idx == UB960_MAX_PORT_ALIASES) { dev_err(dev, "rx%u: alias pool exhausted\n", rxport->nport); - return -EADDRNOTAVAIL; + ret = -EADDRNOTAVAIL; + goto out_unlock; } rxport->aliased_addrs[reg_idx] = client->addr; @@ -1051,7 +1057,9 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, dev_dbg(dev, "rx%u: client 0x%02x assigned alias 0x%02x at slot %u\n", rxport->nport, client->addr, alias, reg_idx); - return 0; +out_unlock: + mutex_unlock(&rxport->aliased_addrs_lock); + return ret; } static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, @@ -1062,6 +1070,8 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, struct device *dev = &priv->client->dev; unsigned int reg_idx; + mutex_lock(&rxport->aliased_addrs_lock); + for (reg_idx = 0; reg_idx < UB960_MAX_PORT_ALIASES; reg_idx++) { if (rxport->aliased_addrs[reg_idx] == client->addr) break; @@ -1070,7 +1080,7 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, if (reg_idx == UB960_MAX_PORT_ALIASES) { dev_err(dev, "rx%u: client 0x%02x is not mapped!\n", rxport->nport, client->addr); - return; + goto out_unlock; } rxport->aliased_addrs[reg_idx] = 0; @@ -1079,6 +1089,9 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, dev_dbg(dev, "rx%u: client 0x%02x released at slot %u\n", rxport->nport, client->addr, reg_idx); + +out_unlock: + mutex_unlock(&rxport->aliased_addrs_lock); } static const struct i2c_atr_ops ub960_atr_ops = { @@ -3181,6 +3194,8 @@ 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; } @@ -3401,6 +3416,8 @@ 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:
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. Signed-off-by: Romain Gantois <romain.gantois@bootlin.com> --- drivers/media/i2c/ds90ub960.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-)