| Message ID | 20210712182121.2936794-1-andy.shevchenko@gmail.com |
|---|---|
| State | Accepted |
| Commit | 71f6428332844f38c7cb10461d9f29e9c9b983a0 |
| Headers | show |
| Series | [v2,1/1] ACPI: utils: Fix reference counting in for_each_acpi_dev_match() | expand |
On Wed, Jul 14, 2021 at 12:32 AM Daniel Scally <djrscally@gmail.com> wrote: > > Hi Andy - thanks for fixing this > > On 12/07/2021 19:21, Andy Shevchenko wrote: > > Currently it's possible to iterate over the dangling pointer in case the device > > suddenly disappears. This may happen becase callers put it at the end of a loop. > > > > Instead, let's move that call inside acpi_dev_get_next_match_dev(). > > > > Fixes: 803abec64ef9 ("media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver") > > Fixes: bf263f64e804 ("media: ACPI / bus: Add acpi_dev_get_next_match_dev() and helper macro") > > Fixes: edbd1bc4951e ("efi/dev-path-parser: Switch to use for_each_acpi_dev_match()") > > Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com> > > Reviewed-by: Daniel Scally <djrscally@gmail.com> Applied as 5.14-rc material, thanks! > > --- > > v2: > > - rebased on top of v5.14-rc1 and hence added fix for EFI code > > - added kernel documentation update to point out that > > acpi_dev_get_next_match_dev() drops a reference on the given > > ACPI device (Rafael) > > > > drivers/acpi/utils.c | 7 +++---- > > drivers/firmware/efi/dev-path-parser.c | 1 - > > drivers/media/pci/intel/ipu3/cio2-bridge.c | 6 ++---- > > include/acpi/acpi_bus.h | 5 ----- > > 4 files changed, 5 insertions(+), 14 deletions(-) > > > > diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c > > index e7ddd281afff..d5cedffeeff9 100644 > > --- a/drivers/acpi/utils.c > > +++ b/drivers/acpi/utils.c > > @@ -860,11 +860,9 @@ EXPORT_SYMBOL(acpi_dev_present); > > * Return the next match of ACPI device if another matching device was present > > * at the moment of invocation, or NULL otherwise. > > * > > - * FIXME: The function does not tolerate the sudden disappearance of @adev, e.g. > > - * in the case of a hotplug event. That said, the caller should ensure that > > - * this will never happen. > > - * > > * The caller is responsible for invoking acpi_dev_put() on the returned device. > > + * On the other hand the function invokes acpi_dev_put() on the given @adev > > + * assuming that its reference counter had been increased beforehand. > > * > > * See additional information in acpi_dev_present() as well. > > */ > > @@ -880,6 +878,7 @@ acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const cha > > match.hrv = hrv; > > > > dev = bus_find_device(&acpi_bus_type, start, &match, acpi_dev_match_cb); > > + acpi_dev_put(adev); > > return dev ? to_acpi_device(dev) : NULL; > > } > > EXPORT_SYMBOL(acpi_dev_get_next_match_dev); > > diff --git a/drivers/firmware/efi/dev-path-parser.c b/drivers/firmware/efi/dev-path-parser.c > > index 10d4457417a4..eb9c65f97841 100644 > > --- a/drivers/firmware/efi/dev-path-parser.c > > +++ b/drivers/firmware/efi/dev-path-parser.c > > @@ -34,7 +34,6 @@ static long __init parse_acpi_path(const struct efi_dev_path *node, > > break; > > if (!adev->pnp.unique_id && node->acpi.uid == 0) > > break; > > - acpi_dev_put(adev); > > } > > if (!adev) > > return -ENODEV; > > diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c > > index 4657e99df033..59a36f922675 100644 > > --- a/drivers/media/pci/intel/ipu3/cio2-bridge.c > > +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c > > @@ -173,10 +173,8 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg, > > int ret; > > > > for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) { > > - if (!adev->status.enabled) { > > - acpi_dev_put(adev); > > + if (!adev->status.enabled) > > continue; > > - } > > > > if (bridge->n_sensors >= CIO2_NUM_PORTS) { > > acpi_dev_put(adev); > > @@ -185,7 +183,6 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg, > > } > > > > sensor = &bridge->sensors[bridge->n_sensors]; > > - sensor->adev = adev; > > strscpy(sensor->name, cfg->hid, sizeof(sensor->name)); > > > > ret = cio2_bridge_read_acpi_buffer(adev, "SSDB", > > @@ -215,6 +212,7 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg, > > goto err_free_swnodes; > > } > > > > + sensor->adev = acpi_dev_get(adev); > > adev->fwnode.secondary = fwnode; > > > > dev_info(&cio2->dev, "Found supported sensor %s\n", > > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h > > index 1ae993fee4a5..b9d434a93632 100644 > > --- a/include/acpi/acpi_bus.h > > +++ b/include/acpi/acpi_bus.h > > @@ -707,11 +707,6 @@ acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv); > > * @hrv: Hardware Revision of the device, pass -1 to not check _HRV > > * > > * The caller is responsible for invoking acpi_dev_put() on the returned device. > > - * > > - * FIXME: Due to above requirement there is a window that may invalidate @adev > > - * and next iteration will use a dangling pointer, e.g. in the case of a > > - * hotplug event. That said, the caller should ensure that this will never > > - * happen. > > */ > > #define for_each_acpi_dev_match(adev, hid, uid, hrv) \ > > for (adev = acpi_dev_get_first_match_dev(hid, uid, hrv); \
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c index e7ddd281afff..d5cedffeeff9 100644 --- a/drivers/acpi/utils.c +++ b/drivers/acpi/utils.c @@ -860,11 +860,9 @@ EXPORT_SYMBOL(acpi_dev_present); * Return the next match of ACPI device if another matching device was present * at the moment of invocation, or NULL otherwise. * - * FIXME: The function does not tolerate the sudden disappearance of @adev, e.g. - * in the case of a hotplug event. That said, the caller should ensure that - * this will never happen. - * * The caller is responsible for invoking acpi_dev_put() on the returned device. + * On the other hand the function invokes acpi_dev_put() on the given @adev + * assuming that its reference counter had been increased beforehand. * * See additional information in acpi_dev_present() as well. */ @@ -880,6 +878,7 @@ acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const cha match.hrv = hrv; dev = bus_find_device(&acpi_bus_type, start, &match, acpi_dev_match_cb); + acpi_dev_put(adev); return dev ? to_acpi_device(dev) : NULL; } EXPORT_SYMBOL(acpi_dev_get_next_match_dev); diff --git a/drivers/firmware/efi/dev-path-parser.c b/drivers/firmware/efi/dev-path-parser.c index 10d4457417a4..eb9c65f97841 100644 --- a/drivers/firmware/efi/dev-path-parser.c +++ b/drivers/firmware/efi/dev-path-parser.c @@ -34,7 +34,6 @@ static long __init parse_acpi_path(const struct efi_dev_path *node, break; if (!adev->pnp.unique_id && node->acpi.uid == 0) break; - acpi_dev_put(adev); } if (!adev) return -ENODEV; diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c index 4657e99df033..59a36f922675 100644 --- a/drivers/media/pci/intel/ipu3/cio2-bridge.c +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c @@ -173,10 +173,8 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg, int ret; for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) { - if (!adev->status.enabled) { - acpi_dev_put(adev); + if (!adev->status.enabled) continue; - } if (bridge->n_sensors >= CIO2_NUM_PORTS) { acpi_dev_put(adev); @@ -185,7 +183,6 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg, } sensor = &bridge->sensors[bridge->n_sensors]; - sensor->adev = adev; strscpy(sensor->name, cfg->hid, sizeof(sensor->name)); ret = cio2_bridge_read_acpi_buffer(adev, "SSDB", @@ -215,6 +212,7 @@ static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg, goto err_free_swnodes; } + sensor->adev = acpi_dev_get(adev); adev->fwnode.secondary = fwnode; dev_info(&cio2->dev, "Found supported sensor %s\n", diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index 1ae993fee4a5..b9d434a93632 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -707,11 +707,6 @@ acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv); * @hrv: Hardware Revision of the device, pass -1 to not check _HRV * * The caller is responsible for invoking acpi_dev_put() on the returned device. - * - * FIXME: Due to above requirement there is a window that may invalidate @adev - * and next iteration will use a dangling pointer, e.g. in the case of a - * hotplug event. That said, the caller should ensure that this will never - * happen. */ #define for_each_acpi_dev_match(adev, hid, uid, hrv) \ for (adev = acpi_dev_get_first_match_dev(hid, uid, hrv); \
Currently it's possible to iterate over the dangling pointer in case the device suddenly disappears. This may happen becase callers put it at the end of a loop. Instead, let's move that call inside acpi_dev_get_next_match_dev(). Fixes: 803abec64ef9 ("media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver") Fixes: bf263f64e804 ("media: ACPI / bus: Add acpi_dev_get_next_match_dev() and helper macro") Fixes: edbd1bc4951e ("efi/dev-path-parser: Switch to use for_each_acpi_dev_match()") Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com> --- v2: - rebased on top of v5.14-rc1 and hence added fix for EFI code - added kernel documentation update to point out that acpi_dev_get_next_match_dev() drops a reference on the given ACPI device (Rafael) drivers/acpi/utils.c | 7 +++---- drivers/firmware/efi/dev-path-parser.c | 1 - drivers/media/pci/intel/ipu3/cio2-bridge.c | 6 ++---- include/acpi/acpi_bus.h | 5 ----- 4 files changed, 5 insertions(+), 14 deletions(-)