[PATCH 8/8] firewire: core: change modalias of unit device with backward incompatibility
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bencollins
From: Takashi S. <o-t...@sa...> - 2023-12-20 04:18:41
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As the last part of support for legacy layout of configuration ROM, this commit traverses vendor directory as well as root directory when constructing modalias for unit device. The change brings loss of backward compatibility since it can fill model field ('mo') which is 0 at current implementation in the case. However, we can be optimistic against regression for unit drivers in kernel, due to some points: 1. ALSA drivers for audio and music units use the model fields to match device, however all of supported devices does not have such legacy layout. 2. the other unit drivers (e.g. sbp2) does not use the model field to match device. The rest of concern is user space application. The most of applications just take care of node device and does not use the modalias of unit device, thus the change does not affect to them. But systemd project is known to get affects from the change since it includes hwdb to take udev to configure fw character device conveniently. I have a plan to work for systemd so that the access permission of character device could be kept across the change. Signed-off-by: Takashi Sakamoto <o-t...@sa...> --- drivers/firewire/core-device.c | 21 +++++++++++++++++++-- drivers/firewire/device-attribute-test.c | 2 +- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c index 2bc6c874e89c..abcb0f036fcd 100644 --- a/drivers/firewire/core-device.c +++ b/drivers/firewire/core-device.c @@ -153,8 +153,25 @@ static void get_ids(const u32 *directory, int *id) static void get_modalias_ids(const struct fw_unit *unit, int *id) { - get_ids(&fw_parent_device(unit)->config_rom[ROOT_DIR_OFFSET], id); - get_ids(unit->directory, id); + const u32 *root_directory = &fw_parent_device(unit)->config_rom[ROOT_DIR_OFFSET]; + const u32 *directories[] = {NULL, NULL, NULL}; + const u32 *vendor_directory; + int i; + + directories[0] = root_directory; + + // Legacy layout of configuration ROM described in Annex 1 of 'Configuration ROM for AV/C + // Devices 1.0 (December 12, 2000, 1394 Trading Association, TA Document 1999027)'. + vendor_directory = search_directory(root_directory, CSR_VENDOR); + if (!vendor_directory) { + directories[1] = unit->directory; + } else { + directories[1] = vendor_directory; + directories[2] = unit->directory; + } + + for (i = 0; i < ARRAY_SIZE(directories) && !!directories[i]; ++i) + get_ids(directories[i], id); } static bool match_ids(const struct ieee1394_device_id *id_table, int *id) diff --git a/drivers/firewire/device-attribute-test.c b/drivers/firewire/device-attribute-test.c index da2a4a09bf84..2f123c6b0a16 100644 --- a/drivers/firewire/device-attribute-test.c +++ b/drivers/firewire/device-attribute-test.c @@ -178,7 +178,7 @@ static void device_attr_legacy_avc(struct kunit *test) }; struct device *node_dev = (struct device *)&node.device; struct device *unit0_dev = (struct device *)&unit0.device; - static const int unit0_expected_ids[] = {0x00012345, 0x00000000, 0x00abcdef, 0x00543210}; + static const int unit0_expected_ids[] = {0x00012345, 0x00fedcba, 0x00abcdef, 0x00543210}; char *buf = kunit_kzalloc(test, PAGE_SIZE, GFP_KERNEL); int ids[4] = {0, 0, 0, 0}; -- 2.39.2 |