[{"id":3678840,"web_url":"http://patchwork.ozlabs.org/comment/3678840/","msgid":"<894A0EA3-66BF-4B53-B44C-EECA28D3595C@netways.de>","list_archive_url":null,"date":"2026-04-17T06:59:13","subject":"Re: [PATCH] module: fix early stop for module loading function","submitter":{"id":93178,"url":"http://patchwork.ozlabs.org/api/people/93178/","name":"Gabriel Hartmann","email":"gabriel.hartmann@netways.de"},"content":"On Wed, Apr 16, 2026 at 01:48:42PM +0000, Hector Cao wrote:\n> The commit c551fb0b53d introduces a regression on the behavior\n> of the module load logic. Historically, if QEMU cannot load a\n> particular module in a folder, it keeps going and look for the\n> module in the remaining folders. The mentioned commit make QEMU\n> stop if the module exists but cannot be loaded (build mismatch\n> reason for example).\n\nThanks for the patch, Hector. I'm the original reporter of this issue\nand have been debugging it on our OpenStack/Ceph production environment.\nThe analysis and both fixes look correct to me. One comment:\n\n> + rv = 0; /* module not found */\n> + for (i = 0; (i < n_dirs) && (rv != 1); i++) {\n> char *fname = g_strdup_printf(\"%s/%s%s\",\n> dirs[i], module_name,\n> CONFIG_HOST_DSOSUF);\n> int ret = access(fname, F_OK);\n> - if (ret != 0 && (errno == ENOENT || errno == ENOTDIR)) {\n> - /*\n> - * if we don't find the module in this dir, try the next one.\n> - * If we don't find it in any dir, that can be fine too: user\n> - * did not install the module. We will return 0 in this case\n> - * with no error set.\n> - */\n> - g_free(fname);\n> - continue;\n> - } else if (ret != 0) {\n> + if ((ret == 0) && module_load_dso(fname, export_symbols, errp)) {\n> + rv = 1; /* module successfully loaded */\n> + }\n> +\n> + /* The file exists but cannot be accessed -> report an error and\n> continue */\n> + if ((ret != 0) && (errno != ENOENT) && (errno != ENOTDIR)) {\n> /* most common is EACCES here */\n> error_setg_errno(errp, errno, \"error trying to access %s\", fname);\n> - } else if (module_load_dso(fname, export_symbols, errp)) {\n> - rv = 1; /* module successfully loaded */\n> }\n\nThe loop can trigger assert(*errp == NULL) inside error_setv() when\nerrors occur in multiple iterations.\n\nConsider: directory 1 contains the module but with a build mismatch.\nmodule_load_dso() returns false and sets *errp. The loop continues to\ndirectory 2, which either also has a mismatched module (calling\nmodule_load_dso() -> error_setg() again) or has an access error\n(calling error_setg_errno()). In both cases, *errp is already set,\nand error_setv() will hit its assert(*errp == NULL).\n\nThe error needs to be freed between iterations, for example:\n\n rv = 0;\n for (i = 0; (i < n_dirs) && (rv != 1); i++) {\n char *fname = g_strdup_printf(\"%s/%s%s\",\n dirs[i], module_name, CONFIG_HOST_DSOSUF);\n int ret = access(fname, F_OK);\n if ((ret == 0) && module_load_dso(fname, export_symbols, errp)) {\n rv = 1;\n }\n\n if ((ret != 0) && (errno != ENOENT) && (errno != ENOTDIR)) {\n error_setg_errno(errp, errno, \"error trying to access %s\", fname);\n }\n\n /* Clear error from this iteration before trying next directory */\n if ((rv != 1) && *errp) {\n error_free(*errp);\n *errp = NULL;\n }\n\n g_free(fname);\n }\n\n /* If we exhausted all dirs without success, set a meaningful error */\n if (rv != 1 && !*errp) {\n error_setg(errp, \"could not load module '%s'\", module_name);\n }\n\nAlternatively, using a local Error *local_err = NULL and only\npropagating the last error at the end would follow the common QEMU\npattern more closely.\n\n-- \nGabriel Hartmann\nSenior Systems Engineer\n\nNETWAYS Managed Services GmbH | Deutschherrnstr. 15-19 | D-90429 Nuernberg\nTel: +49 911 92885-0 | Fax: +49 911 92885-77\nCEO: Julian Hein, Bernd Erk, Sebastian Saemann | AG Nuernberg HRB25207\nhttps://www.netways.de | gabriel.hartmann@netways.de\n\n** stackconf 2026 - April | Munich - https://stackconf.eu **\n** Open Source Monitoring Conference 2026 - November | Nuremberg - https://osmc.de **\n** NETWAYS Web Services - https://nws.netways.de **\n** NETWAYS Trainings - https://netways.de/trainings **","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=netways.de header.i=@netways.de header.a=rsa-sha256\n header.s=20241115 header.b=n+kPw+NZ;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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