Messages in this thread | | | Date | Wed, 8 Apr 2020 17:02:00 -0700 | From | Lucas De Marchi <> | Subject | Re: RFC: Handle hard module dependencies that are not symbol-based (r8169 + realtek) |
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On Wed, Apr 01, 2020 at 11:20:20PM +0200, Heiner Kallweit wrote: >Currently we have no way to express a hard dependency that is not >a symbol-based dependency (symbol defined in module A is used in >module B). Use case: >Network driver ND uses callbacks in the dedicated PHY driver DP >for the integrated PHY (namely read_page() and write_page() in >struct phy_driver). If DP can't be loaded (e.g. because ND is in >initramfs but DP is not), then phylib will use the generic >PHY driver GP. GP doesn't implement certain callbacks that are >needed by ND, therefore ND's probe has to bail out with an error >once it detects that DP is not loaded. >We have this problem with driver r8169 having such a dependency >on PHY driver realtek. Some distributions have tools for >configuring initramfs that consider hard dependencies based on >depmod output. Means so far somebody can add r8169.ko to initramfs, >and neither human being nor machine will have an idea that >realtek.ko needs to be added too.
Could you expand on why softdep doesn't solve this problem with MODULE_SOFTDEP()
initramfs tools can already read it and modules can already expose them (they end up in /lib/modules/$(uname -r)/modules.softdep and modprobe makes use of them)
Lucas De Marchi
> >Attached patch set (two patches for kmod, one for the kernel) >allows to express this hard dependency of ND from DP. depmod will >read this dependency information and treat it like a symbol-based >dependency. As a result tools e.g. populating initramfs can >consider the dependency and place DP in initramfs if ND is in >initramfs. On my system the patch set does the trick when >adding following line to r8169_main.c: >MODULE_HARDDEP("realtek"); > >I'm interested in your opinion on the patches, and whether you >maybe have a better idea how to solve the problem. > >Heiner
>From 290e7dee9f6043d677f08dc06e612e13ee0d2d83 Mon Sep 17 00:00:00 2001 >From: Heiner Kallweit <hkallweit1@gmail.com> >Date: Tue, 31 Mar 2020 23:02:47 +0200 >Subject: [PATCH 1/2] depmod: add helper mod_add_dep_unique > >Create new helper mod_add_dep_unique(), next patch in this series will >also make use of it. > >Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> >--- > tools/depmod.c | 26 +++++++++++++++++++------- > 1 file changed, 19 insertions(+), 7 deletions(-) > >diff --git a/tools/depmod.c b/tools/depmod.c >index 875e314..5419d4d 100644 >--- a/tools/depmod.c >+++ b/tools/depmod.c >@@ -907,23 +907,35 @@ static void mod_free(struct mod *mod) > free(mod); > } > >-static int mod_add_dependency(struct mod *mod, struct symbol *sym) >+static int mod_add_dep_unique(struct mod *mod, struct mod *dep) > { > int err; > >- DBG("%s depends on %s %s\n", mod->path, sym->name, >- sym->owner != NULL ? sym->owner->path : "(unknown)"); >- >- if (sym->owner == NULL) >+ if (dep == NULL) > return 0; > >- err = array_append_unique(&mod->deps, sym->owner); >+ err = array_append_unique(&mod->deps, dep); > if (err == -EEXIST) > return 0; > if (err < 0) > return err; > >- sym->owner->users++; >+ dep->users++; >+ >+ return 1; >+} >+ >+static int mod_add_dependency(struct mod *mod, struct symbol *sym) >+{ >+ int err; >+ >+ DBG("%s depends on %s %s\n", mod->path, sym->name, >+ sym->owner != NULL ? sym->owner->path : "(unknown)"); >+ >+ err = mod_add_dep_unique(mod, sym->owner); >+ if (err <= 0) >+ return err; >+ > SHOW("%s needs \"%s\": %s\n", mod->path, sym->name, sym->owner->path); > return 0; > } >-- >2.26.0 >
>From b12fa0d85b21d84cdf4509c5048c67e17914eb28 Mon Sep 17 00:00:00 2001 >From: Heiner Kallweit <hkallweit1@gmail.com> >Date: Mon, 30 Mar 2020 17:12:44 +0200 >Subject: [PATCH] module: add MODULE_HARDDEP > >Currently we have no way to express a hard dependency that is not a >symbol-based dependency (symbol defined in module A is used in >module B). Use case: >Network driver ND uses callbacks in the dedicated PHY driver DP >for the integrated PHY. If DP can't be loaded (e.g. because ND >is in initramfs but DP is not), then phylib will load the generic >PHY driver GP. GP doesn't implement certain callbacks that are >used by ND, therefore ND's probe has to bail out with an error >once it detects that DP is not loaded. >This patch allows to express this hard dependency of ND from DP. >depmod will read this dependency information and treat it like >a symbol-based dependency. As a result tools e.g. populating >initramfs can consider the dependency and place DP in initramfs >if ND is in initramfs. > >Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> >--- > include/linux/module.h | 5 +++++ > 1 file changed, 5 insertions(+) > >diff --git a/include/linux/module.h b/include/linux/module.h >index 1ad393e62..f38d4107f 100644 >--- a/include/linux/module.h >+++ b/include/linux/module.h >@@ -169,6 +169,11 @@ extern void cleanup_module(void); > */ > #define MODULE_SOFTDEP(_softdep) MODULE_INFO(softdep, _softdep) > >+/* Hard module dependencies that are not code dependencies >+ * Example: MODULE_HARDDEP("module-foo module-bar") >+ */ >+#define MODULE_HARDDEP(_harddep) MODULE_INFO(harddep, _harddep) >+ > /* > * MODULE_FILE is used for generating modules.builtin > * So, make it no-op when this is being built as a module >-- >2.26.0 >
>From af3a25833a160e029441eaf5a93f7c8625544296 Mon Sep 17 00:00:00 2001 >From: Heiner Kallweit <hkallweit1@gmail.com> >Date: Wed, 1 Apr 2020 22:42:55 +0200 >Subject: [PATCH 2/2] depmod: add depmod_load_harddeps > >Load explicitly declared hard dependency information from modules and >add it to the symbol-derived dependencies. This will allow >depmod-based tools to consider hard dependencies that are not code >dependencies. > >Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> >--- > tools/depmod.c | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > >diff --git a/tools/depmod.c b/tools/depmod.c >index 5419d4d..5771dc9 100644 >--- a/tools/depmod.c >+++ b/tools/depmod.c >@@ -1522,6 +1522,41 @@ static struct symbol *depmod_symbol_find(const struct depmod *depmod, > return hash_find(depmod->symbols, name); > } > >+static void depmod_load_harddeps(struct depmod *depmod, struct mod *mod) >+{ >+ >+ struct kmod_list *l; >+ >+ kmod_list_foreach(l, mod->info_list) { >+ const char *key = kmod_module_info_get_key(l); >+ const char *dep_name; >+ struct mod *dep; >+ char *value; >+ >+ if (!streq(key, "harddep")) >+ continue; >+ >+ value = strdup(kmod_module_info_get_value(l)); >+ if (value == NULL) >+ return; >+ >+ dep_name = strtok(value, " \t"); >+ >+ while (dep_name) { >+ dep = hash_find(depmod->modules_by_name, dep_name); >+ if (dep) >+ mod_add_dep_unique(mod, dep); >+ else >+ WRN("harddep: %s: unknown dependency %s\n", >+ mod->modname, dep_name); >+ >+ dep_name = strtok(NULL, " \t"); >+ } >+ >+ free(value); >+ } >+} >+ > static int depmod_load_modules(struct depmod *depmod) > { > struct mod **itr, **itr_end; >@@ -1569,6 +1604,9 @@ static int depmod_load_module_dependencies(struct depmod *depmod, struct mod *mo > struct kmod_list *l; > > DBG("do dependencies of %s\n", mod->path); >+ >+ depmod_load_harddeps(depmod, mod); >+ > kmod_list_foreach(l, mod->dep_sym_list) { > const char *name = kmod_module_dependency_symbol_get_symbol(l); > uint64_t crc = kmod_module_dependency_symbol_get_crc(l); >-- >2.26.0 >
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