namei (via firmware_get(9)) from taskq in 7.x
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namei (via firmware_get(9)) from taskq in 7.x
by Andrew Gallatin
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Re: namei (via firmware_get(9)) from taskq in 7.x
by Kostik Belousov
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On Thu, Oct 15, 2009 at 05:16:22PM -0400, Andrew Gallatin wrote:
> Hi, > > I'm trying to re-initialize a NIC which uses firmware(9) > after a hardware fault. As part of the process, I need > to re-load the firmware using firmware_get(). If the > firmware kld is not resident, then the machine will panic > like this: > > Fatal trap 12: page fault while in kernel mode > cpuid = 0; apic id = 00 > fault virtual address = 0x20 > fault code = supervisor read data, page not present > instruction pointer = 0x8:0xffffffff805b05d4 > stack pointer = 0x10:0xffffff8000080460 > frame pointer = 0x10:0xffffff8000080510 > code segment = base 0x0, limit 0xfffff, type 0x1b > = DPL 0, pres 1, long 1, def32 0, gran 1 > processor eflags = interrupt enabled, resume, IOPL = 0 > current process = 21 (swi5: +) > [thread pid 21 tid 100021 ] > Stopped at namei+0x174: movq 0x20(%rbx),%rax > db> bt > Tracing pid 21 tid 100021 td 0xffffff00013c3ae0 > namei() at namei+0x174 > vn_open_cred() at vn_open_cred+0x3a4 > linker_load_module() at linker_load_module+0x1f2 > linker_reference_module() at linker_reference_module+0xae > firmware_get() at firmware_get+0x136 > mxge_load_firmware() at mxge_load_firmware+0x2d > mxge_watchdog_task() at mxge_watchdog_task+0x2f6 > taskqueue_run() at taskqueue_run+0x9d > ithread_loop() at ithread_loop+0x17d > fork_exit() at fork_exit+0x11f > fork_trampoline() at fork_trampoline+0xe > > Looking at it in gdb, it seems like the problem is that namei > is trying to use ndp->ni_cnd.cn_thread->td_proc->p_fd->fd_cdir > which is null in this context. > > Can somebody tell me what kernel context it is safe to > call firmware_get() (and hence namei) from? Is there > a safe way to do it from a taskq? > > FWIW, this seems to work fine (even from a callout context) > in 8 and higher. It is only 7 and earlier where I'm having > this problem. which is yours). Property changes on: . ___________________________________________________________________ Modified: svn:mergeinfo Merged /head/sys:r178042,183614,184842,188057 Index: kern/subr_firmware.c =================================================================== --- kern/subr_firmware.c (revision 198202) +++ kern/subr_firmware.c (working copy) @@ -1,5 +1,5 @@ /*- - * Copyright (c) 2005, Sam Leffler <sam@...> + * Copyright (c) 2005-2008, Sam Leffler <sam@...> * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -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 +250,47 @@ 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); + + 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) { + mtx_unlock(&firmware_mtx); + if (fp == NULL) + printf("%s: firmware image loaded, " + "but did not register\n", imagename); + (void) linker_release_module(imagename, NULL, NULL); + goto done; + } + 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 +301,9 @@ 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 +312,34 @@ /* * 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. + */ + if (!cold) { + 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 +352,8 @@ * 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 +366,53 @@ 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); + + free(arg, M_TEMP); +} + +/* + * 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) +{ + struct task *setroot_task; + + setroot_task = malloc(sizeof(struct task), M_TEMP, M_NOWAIT); + if (setroot_task != NULL) { + TASK_INIT(setroot_task, 0, set_rootvnode, setroot_task); + taskqueue_enqueue(firmware_tq, setroot_task); + } else + printf("%s: no memory for task!\n", __func__); +} +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 +476,23 @@ 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"); + if (rootvnode != NULL) { + /* + * Root is already mounted so we won't get an event; + * simulate one here. + */ + firmware_mountroot(NULL); + } return 0; case MOD_UNLOAD: @@ -398,8 +503,9 @@ 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 +515,8 @@ err = EINVAL; } } + if (err == 0) + taskqueue_free(firmware_tq); return err; } return EINVAL; @@ -417,7 +525,7 @@ static moduledata_t firmware_mod = { "firmware", firmware_modevent, - 0 + NULL }; DECLARE_MODULE(firmware, firmware_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST); MODULE_VERSION(firmware, 1); Property changes on: kern/subr_firmware.c ___________________________________________________________________ Modified: cvs2svn:cvs-rev - 1.9 + 1.10 Index: kern/subr_prf.c =================================================================== --- kern/subr_prf.c (revision 198202) +++ kern/subr_prf.c (working copy) @@ -955,7 +955,7 @@ } SYSCTL_PROC(_kern, OID_AUTO, msgbuf, CTLTYPE_STRING | CTLFLAG_RD, - 0, 0, sysctl_kern_msgbuf, "A", "Contents of kernel message buffer"); + NULL, 0, sysctl_kern_msgbuf, "A", "Contents of kernel message buffer"); static int msgbuf_clearflag; Property changes on: contrib/pf ___________________________________________________________________ Modified: svn:mergeinfo Merged /head/sys/contrib/pf:r178042,183614,184842,188057 |
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Re: namei (via firmware_get(9)) from taskq in 7.x
by Andrew Gallatin
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