Date: Mon, 7 Apr 2008 21:29:24 GMT From: Sam Leffler <sam@FreeBSD.org> To: Perforce Change Reviews <perforce@freebsd.org> Subject: PERFORCE change 139545 for review Message-ID: <200804072129.m37LTOTQ096269@repoman.freebsd.org>
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http://perforce.freebsd.org/chv.cgi?CH=139545 Change 139545 by sam@sam_ebb on 2008/04/07 21:28:26 Fix longstanding issue with firmware_get requests blowing up due to the thread not having sufficient context to do file i/o: o create a private taskqueue and thread and setup the thread with root+current directory o bounce module load requests to the private thread so we know i/o can be done o use private q+thread for unload requests too Affected files ... .. //depot/projects/vap/sys/kern/subr_firmware.c#3 edit Differences ... ==== //depot/projects/vap/sys/kern/subr_firmware.c#3 (text+ko) ==== @@ -41,7 +41,11 @@ #include <sys/priv.h> #include <sys/proc.h> #include <sys/module.h> +#include <sys/eventhandler.h> +#include <sys/filedesc.h> +#include <sys/vnode.h> + /* * Loadable firmware support. See sys/sys/firmware.h and firmware(9) * form more details on the subsystem. @@ -89,7 +93,7 @@ /* * 'file' is private info managed by the autoload/unload code. * Set at the end of firmware_get(), cleared only in the - * firmware_task, so the latter can depend on its value even + * firmware_unload_task, so the latter can depend on its value even * while the lock is not held. */ linker_file_t file; /* module file, if autoloaded */ @@ -121,14 +125,16 @@ static struct priv_fw firmware_table[FIRMWARE_MAX]; /* - * module release are handled in a separate task as they might sleep. + * Firmware module operations are handled in a separate task as they + * might sleep and they require directory context to do i/o. */ -struct task firmware_task; +static struct taskqueue *firmware_tq; +static struct task firmware_unload_task; /* * This mutex protects accesses to the firmware table. */ -struct mtx firmware_mtx; +static struct mtx firmware_mtx; MTX_SYSINIT(firmware, &firmware_mtx, "firmware table", MTX_DEF); /* @@ -227,7 +233,7 @@ } else if (fp->refcnt != 0) { /* cannot unregister */ err = EBUSY; } else { - linker_file_t x = fp->file; /* save value */ + linker_file_t x = fp->file; /* save value */ if (fp->parent != NULL) /* release parent reference */ fp->parent->refcnt--; @@ -244,6 +250,46 @@ return err; } +static void +loadimage(void *arg, int npending) +{ + struct thread *td = curthread; + char *imagename = arg; + struct priv_fw *fp; + linker_file_t result; + int error; + + /* synchronize with the thread that dispatched us */ + mtx_lock(&firmware_mtx); + mtx_unlock(&firmware_mtx); + + /* XXX unlocked, necessary? */ + if (td->td_proc->p_fd->fd_rdir == NULL) { + printf("%s: root not mounted yet, no way to load image\n", + imagename); + goto done; + } + error = linker_reference_module(imagename, NULL, &result); + if (error != 0) { + printf("%s: could not load firmware image, error %d\n", + imagename, error); + goto done; + } + + mtx_lock(&firmware_mtx); + fp = lookup(imagename, NULL); + if (fp == NULL || fp->file != NULL) { + if (fp == NULL) + printf("%s: firmware image loaded, " + "but did not register\n", imagename); + (void) linker_release_module(imagename, NULL, NULL); + } else + fp->file = result; /* record the module identity */ + mtx_unlock(&firmware_mtx); +done: + wakeup_one(imagename); /* we're done */ +} + /* * Lookup and potentially load the specified firmware image. * If the firmware is not found in the registry, try to load a kernel @@ -254,9 +300,9 @@ const struct firmware * firmware_get(const char *imagename) { + struct task fwload_task; struct thread *td; struct priv_fw *fp; - linker_file_t result; mtx_lock(&firmware_mtx); fp = lookup(imagename, NULL); @@ -265,29 +311,30 @@ /* * Image not present, try to load the module holding it. */ - mtx_unlock(&firmware_mtx); td = curthread; if (priv_check(td, PRIV_FIRMWARE_LOAD) != 0 || securelevel_gt(td->td_ucred, 0) != 0) { + mtx_unlock(&firmware_mtx); printf("%s: insufficient privileges to " "load firmware image %s\n", __func__, imagename); return NULL; } - (void) linker_reference_module(imagename, NULL, &result); + /* + * Defer load to a thread with known context. linker_reference_module + * may do filesystem i/o which requires root & current dirs, etc. + * Also we must not hold any mtx's over this call which is problematic. + */ + TASK_INIT(&fwload_task, 0, loadimage, __DECONST(void *, imagename)); + taskqueue_enqueue(firmware_tq, &fwload_task); + msleep(__DECONST(void *, imagename), &firmware_mtx, 0, "fwload", 0); /* - * After loading the module, see if the image is registered now. + * After attempting to load the module, see if the image is registered. */ - mtx_lock(&firmware_mtx); fp = lookup(imagename, NULL); if (fp == NULL) { mtx_unlock(&firmware_mtx); - printf("%s: failed to load firmware image %s\n", - __func__, imagename); - (void) linker_release_module(imagename, NULL, NULL); return NULL; } - fp->file = result; /* record the module identity */ - found: /* common exit point on success */ fp->refcnt++; mtx_unlock(&firmware_mtx); @@ -300,8 +347,8 @@ * to release the resource, but the flag is only advisory. * * If this is the last reference to the firmware image, and this is an - * autoloaded module, wake up the firmware_task to figure out what to do - * with the associated module. + * autoloaded module, wake up the firmware_unload_task to figure out + * what to do with the associated module. */ void firmware_put(const struct firmware *p, int flags) @@ -314,12 +361,47 @@ if (flags & FIRMWARE_UNLOAD) fp->flags |= FW_UNLOAD; if (fp->file) - taskqueue_enqueue(taskqueue_thread, &firmware_task); + taskqueue_enqueue(firmware_tq, &firmware_unload_task); } mtx_unlock(&firmware_mtx); } /* + * Setup directory state for the firmware_tq thread so we can do i/o. + */ +static void +set_rootvnode(void *arg, int npending) +{ + struct thread *td = curthread; + struct proc *p = td->td_proc; + + FILEDESC_XLOCK(p->p_fd); + if (p->p_fd->fd_cdir == NULL) { + p->p_fd->fd_cdir = rootvnode; + VREF(rootvnode); + } + if (p->p_fd->fd_rdir == NULL) { + p->p_fd->fd_rdir = rootvnode; + VREF(rootvnode); + } + FILEDESC_XUNLOCK(p->p_fd); +} + +/* + * Event handler called on mounting of /. Bounce a task + * into the task queue thread to setup it's directories. + */ +static void +firmware_mountroot(void *arg) +{ + static struct task setroot_task; + + TASK_INIT(&setroot_task, 0, set_rootvnode, NULL); + taskqueue_enqueue(firmware_tq, &setroot_task); +} +EVENTHANDLER_DEFINE(mountroot, firmware_mountroot, NULL, 0); + +/* * The body of the task in charge of unloading autoloaded modules * that are not needed anymore. * Images can be cross-linked so we may need to make multiple passes, @@ -383,11 +465,16 @@ firmware_modevent(module_t mod, int type, void *unused) { struct priv_fw *fp; - int i, err = EINVAL; + int i, err; switch (type) { case MOD_LOAD: - TASK_INIT(&firmware_task, 0, unloadentry, NULL); + TASK_INIT(&firmware_unload_task, 0, unloadentry, NULL); + firmware_tq = taskqueue_create("taskqueue_firmware", M_WAITOK, + taskqueue_thread_enqueue, &firmware_tq); + /* NB: use our own loop routine that sets up context */ + (void) taskqueue_start_threads(&firmware_tq, 1, PWAIT, + "firmware taskq"); return 0; case MOD_UNLOAD: @@ -398,8 +485,9 @@ fp->flags |= FW_UNLOAD;; } mtx_unlock(&firmware_mtx); - taskqueue_enqueue(taskqueue_thread, &firmware_task); - taskqueue_drain(taskqueue_thread, &firmware_task); + taskqueue_enqueue(firmware_tq, &firmware_unload_task); + taskqueue_drain(firmware_tq, &firmware_unload_task); + err = 0; for (i = 0; i < FIRMWARE_MAX; i++) { fp = &firmware_table[i]; if (fp->fw.name != NULL) { @@ -409,6 +497,8 @@ err = EINVAL; } } + if (err == 0) + taskqueue_free(firmware_tq); return err; } return EINVAL;
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