Date: Fri, 14 Jul 2006 16:40:22 GMT From: John Baldwin <jhb@FreeBSD.org> To: Perforce Change Reviews <perforce@freebsd.org> Subject: PERFORCE change 101572 for review Message-ID: <200607141640.k6EGeMRN006471@repoman.freebsd.org>
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http://perforce.freebsd.org/chv.cgi?CH=101572 Change 101572 by jhb@jhb_mutex on 2006/07/14 16:39:44 Use a mutex to protect the list of config_intr_hook's. In order to handle the case where a driver might get an interrupt and ask to remove its handler while the previous handler in the list is running, fixup the next_entry handler if needed when a handler is disestablished. To make that work, use an sx lock to ensure only one thread can run the current list of hooks at a time. Affected files ... .. //depot/projects/smpng/sys/kern/subr_autoconf.c#7 edit Differences ... ==== //depot/projects/smpng/sys/kern/subr_autoconf.c#7 (text+ko) ==== @@ -39,7 +39,10 @@ #include <sys/param.h> #include <sys/kernel.h> +#include <sys/lock.h> +#include <sys/mutex.h> #include <sys/systm.h> +#include <sys/sx.h> /* * Autoconfiguration subroutines. @@ -50,26 +53,49 @@ */ static TAILQ_HEAD(, intr_config_hook) intr_config_hook_list = TAILQ_HEAD_INITIALIZER(intr_config_hook_list); +static struct mtx intr_config_hook_lock; +MTX_SYSINIT(intr_config_hook, &intr_config_hook_lock, "intr config", MTX_DEF); +static struct sx intr_config_run_lock; +SX_SYSINIT(intr_config_run, &intr_config_run_lock, "intr config run"); +/* + * The current location in the list when a thread is executing the current + * hooks. If this hook is removed we advance it to the next entry. + */ +static struct intr_config_hook *next_entry; /* ARGSUSED */ static void run_interrupt_driven_config_hooks(void *dummy); + static void run_interrupt_driven_config_hooks(dummy) void *dummy; { - struct intr_config_hook *hook_entry, *next_entry; + struct intr_config_hook *hook_entry; + + /* + * Because of the special care for next_entry, we can only allow one + * thread at a time to run through the list. + */ + sx_xlock(&intr_config_run_lock); + mtx_lock(&intr_config_hook_lock); for (hook_entry = TAILQ_FIRST(&intr_config_hook_list); hook_entry != NULL; hook_entry = next_entry) { next_entry = TAILQ_NEXT(hook_entry, ich_links); + mtx_unlock(&intr_config_hook_lock); (*hook_entry->ich_func)(hook_entry->ich_arg); + mtx_lock(&intr_config_hook_lock); } while (!TAILQ_EMPTY(&intr_config_hook_list)) { - tsleep(&intr_config_hook_list, PCONFIG, "conifhk", 0); + msleep(&intr_config_hook_list, &intr_config_hook_lock, PCONFIG, + "conifhk", 0); } + mtx_unlock(&intr_config_hook_lock); + + sx_xunlock(&intr_config_run_lock); } SYSINIT(intr_config_hooks, SI_SUB_INT_CONFIG_HOOKS, SI_ORDER_FIRST, run_interrupt_driven_config_hooks, NULL) @@ -85,17 +111,18 @@ { struct intr_config_hook *hook_entry; - for (hook_entry = TAILQ_FIRST(&intr_config_hook_list); - hook_entry != NULL; - hook_entry = TAILQ_NEXT(hook_entry, ich_links)) + mtx_lock(&intr_config_hook_lock); + TAILQ_FOREACH(hook_entry, &intr_config_hook_list, ich_links) if (hook_entry == hook) break; if (hook_entry != NULL) { + mtx_unlock(&intr_config_hook_lock); printf("config_intrhook_establish: establishing an " "already established hook.\n"); return (1); } TAILQ_INSERT_TAIL(&intr_config_hook_list, hook, ich_links); + mtx_unlock(&intr_config_hook_lock); if (cold == 0) /* XXX Sufficient for modules loaded after initial config??? */ run_interrupt_driven_config_hooks(NULL); @@ -108,16 +135,23 @@ { struct intr_config_hook *hook_entry; - for (hook_entry = TAILQ_FIRST(&intr_config_hook_list); - hook_entry != NULL; - hook_entry = TAILQ_NEXT(hook_entry, ich_links)) + mtx_lock(&intr_config_hook_lock); + TAILQ_FOREACH(hook_entry, &intr_config_hook_list, ich_links) if (hook_entry == hook) break; if (hook_entry == NULL) panic("config_intrhook_disestablish: disestablishing an " "unestablished hook"); + /* + * If a thread is going to run this hook next, advance it's next + * pointer. + */ + if (hook == next_entry) + next_entry = TAILQ_NEXT(next_entry, ich_links); TAILQ_REMOVE(&intr_config_hook_list, hook, ich_links); + /* Wakeup anyone watching the list */ wakeup(&intr_config_hook_list); + mtx_unlock(&intr_config_hook_lock); }
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