After a recent change in clang to expose uninitialized warnings from const variables [1], there is a warning in cxacru_heavy_init():
drivers/usb/atm/cxacru.c:1104:6: error: variable 'bp' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized] 1104 | if (instance->modem_type->boot_rom_patch) { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/usb/atm/cxacru.c:1113:39: note: uninitialized use occurs here 1113 | cxacru_upload_firmware(instance, fw, bp); | ^~ drivers/usb/atm/cxacru.c:1104:2: note: remove the 'if' if its condition is always true 1104 | if (instance->modem_type->boot_rom_patch) { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/usb/atm/cxacru.c:1095:32: note: initialize the variable 'bp' to silence this warning 1095 | const struct firmware *fw, *bp; | ^ | = NULL
While the warning is technically correct that bp is conditionally passed uninitialized to cxacru_upload_firmware(), it is ultimately a false positive warning on the uninitialized use of bp because the same condition that initializes bp, instance->modem_type->boot_rom_patch, is the same one that gates the use of bp within cxacru_upload_firmware(). As this warning occurs in clang's frontend before inlining occurs, it cannot know that these conditions are indentical to avoid the warning.
Manually inline cxacru_upload_firmware() into cxacru_heavy_init(), as that is its only callsite, so that clang can see that bp is initialized and used under the same condition, clearing up the warning without any functional changes to the code (LLVM was already doing this inlining later).
Cc: stable@vger.kernel.org Fixes: 1b0e61465234 ("[PATCH] USB ATM: driver for the Conexant AccessRunner chipset cxacru") Closes: https://github.com/ClangBuiltLinux/linux/issues/2102 Link: https://github.com/llvm/llvm-project/commit/2464313eef01c5b1edf0eccf57a32cde... [1] Signed-off-by: Nathan Chancellor nathan@kernel.org --- Changes in v2: - Rather than initialize bp to NULL, manually inline cxacru_upload_firmware() into cxacru_heavy_init() so that clang can see the matching conditions for bp's initialization and use (based on feedback from Greg). - Drop accessrunner-general@lists.sourceforge.net, as I got bounces when sending to it unsubscribed. - Link to v1: https://lore.kernel.org/r/20250715-usb-cxacru-fix-clang-21-uninit-warning-v1... --- drivers/usb/atm/cxacru.c | 106 ++++++++++++++++++++++------------------------- 1 file changed, 49 insertions(+), 57 deletions(-)
diff --git a/drivers/usb/atm/cxacru.c b/drivers/usb/atm/cxacru.c index a12ab90b3db75b230dcf319a949e6d10dbac0363..68a8e9de8b4fe95be31b561f7f5df7e3c59142ae 100644 --- a/drivers/usb/atm/cxacru.c +++ b/drivers/usb/atm/cxacru.c @@ -980,25 +980,60 @@ static int cxacru_fw(struct usb_device *usb_dev, enum cxacru_fw_request fw, return ret; }
-static void cxacru_upload_firmware(struct cxacru_data *instance, - const struct firmware *fw, - const struct firmware *bp) + +static int cxacru_find_firmware(struct cxacru_data *instance, + char *phase, const struct firmware **fw_p) { - int ret; + struct usbatm_data *usbatm = instance->usbatm; + struct device *dev = &usbatm->usb_intf->dev; + char buf[16]; + + sprintf(buf, "cxacru-%s.bin", phase); + usb_dbg(usbatm, "cxacru_find_firmware: looking for %s\n", buf); + + if (request_firmware(fw_p, buf, dev)) { + usb_dbg(usbatm, "no stage %s firmware found\n", phase); + return -ENOENT; + } + + usb_info(usbatm, "found firmware %s\n", buf); + + return 0; +} + +static int cxacru_heavy_init(struct usbatm_data *usbatm_instance, + struct usb_interface *usb_intf) +{ + const struct firmware *fw, *bp; + struct cxacru_data *instance = usbatm_instance->driver_data; struct usbatm_data *usbatm = instance->usbatm; struct usb_device *usb_dev = usbatm->usb_dev; __le16 signature[] = { usb_dev->descriptor.idVendor, usb_dev->descriptor.idProduct }; __le32 val; + int ret;
- usb_dbg(usbatm, "%s\n", __func__); + ret = cxacru_find_firmware(instance, "fw", &fw); + if (ret) { + usb_warn(usbatm_instance, "firmware (cxacru-fw.bin) unavailable (system misconfigured?)\n"); + return ret; + } + + if (instance->modem_type->boot_rom_patch) { + ret = cxacru_find_firmware(instance, "bp", &bp); + if (ret) { + usb_warn(usbatm_instance, "boot ROM patch (cxacru-bp.bin) unavailable (system misconfigured?)\n"); + release_firmware(fw); + return ret; + } + }
/* FirmwarePllFClkValue */ val = cpu_to_le32(instance->modem_type->pll_f_clk); ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, PLLFCLK_ADDR, (u8 *) &val, 4); if (ret) { usb_err(usbatm, "FirmwarePllFClkValue failed: %d\n", ret); - return; + goto done; }
/* FirmwarePllBClkValue */ @@ -1006,7 +1041,7 @@ static void cxacru_upload_firmware(struct cxacru_data *instance, ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, PLLBCLK_ADDR, (u8 *) &val, 4); if (ret) { usb_err(usbatm, "FirmwarePllBClkValue failed: %d\n", ret); - return; + goto done; }
/* Enable SDRAM */ @@ -1014,7 +1049,7 @@ static void cxacru_upload_firmware(struct cxacru_data *instance, ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, SDRAMEN_ADDR, (u8 *) &val, 4); if (ret) { usb_err(usbatm, "Enable SDRAM failed: %d\n", ret); - return; + goto done; }
/* Firmware */ @@ -1022,7 +1057,7 @@ static void cxacru_upload_firmware(struct cxacru_data *instance, ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, FW_ADDR, fw->data, fw->size); if (ret) { usb_err(usbatm, "Firmware upload failed: %d\n", ret); - return; + goto done; }
/* Boot ROM patch */ @@ -1031,7 +1066,7 @@ static void cxacru_upload_firmware(struct cxacru_data *instance, ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, BR_ADDR, bp->data, bp->size); if (ret) { usb_err(usbatm, "Boot ROM patching failed: %d\n", ret); - return; + goto done; } }
@@ -1039,7 +1074,7 @@ static void cxacru_upload_firmware(struct cxacru_data *instance, ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, SIG_ADDR, (u8 *) signature, 4); if (ret) { usb_err(usbatm, "Signature storing failed: %d\n", ret); - return; + goto done; }
usb_info(usbatm, "starting device\n"); @@ -1051,7 +1086,7 @@ static void cxacru_upload_firmware(struct cxacru_data *instance, } if (ret) { usb_err(usbatm, "Passing control to firmware failed: %d\n", ret); - return; + goto done; }
/* Delay to allow firmware to start up. */ @@ -1065,53 +1100,10 @@ static void cxacru_upload_firmware(struct cxacru_data *instance, ret = cxacru_cm(instance, CM_REQUEST_CARD_GET_STATUS, NULL, 0, NULL, 0); if (ret < 0) { usb_err(usbatm, "modem failed to initialize: %d\n", ret); - return; - } -} - -static int cxacru_find_firmware(struct cxacru_data *instance, - char *phase, const struct firmware **fw_p) -{ - struct usbatm_data *usbatm = instance->usbatm; - struct device *dev = &usbatm->usb_intf->dev; - char buf[16]; - - sprintf(buf, "cxacru-%s.bin", phase); - usb_dbg(usbatm, "cxacru_find_firmware: looking for %s\n", buf); - - if (request_firmware(fw_p, buf, dev)) { - usb_dbg(usbatm, "no stage %s firmware found\n", phase); - return -ENOENT; - } - - usb_info(usbatm, "found firmware %s\n", buf); - - return 0; -} - -static int cxacru_heavy_init(struct usbatm_data *usbatm_instance, - struct usb_interface *usb_intf) -{ - const struct firmware *fw, *bp; - struct cxacru_data *instance = usbatm_instance->driver_data; - int ret = cxacru_find_firmware(instance, "fw", &fw); - - if (ret) { - usb_warn(usbatm_instance, "firmware (cxacru-fw.bin) unavailable (system misconfigured?)\n"); - return ret; + goto done; }
- if (instance->modem_type->boot_rom_patch) { - ret = cxacru_find_firmware(instance, "bp", &bp); - if (ret) { - usb_warn(usbatm_instance, "boot ROM patch (cxacru-bp.bin) unavailable (system misconfigured?)\n"); - release_firmware(fw); - return ret; - } - } - - cxacru_upload_firmware(instance, fw, bp); - +done: if (instance->modem_type->boot_rom_patch) release_firmware(bp); release_firmware(fw);
--- base-commit: fdfa018c6962c86d2faa183187669569be4d513f change-id: 20250715-usb-cxacru-fix-clang-21-uninit-warning-9430d96c6bc1
Best regards,