From 05537b9db1fff40ca0c85e52bc492808c5d10cf2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Mon, 25 Mar 2019 14:49:00 -0700 Subject: [PATCH] Revert "parport: daisy: use new parport device model" This reverts commit b2c9e5053786543100190e1e8766d04c49b12f4b. Steven Rostedt reports that it causes a hang at bootup and bisected it to this commit. The troigger is apparently a module alias for "parport_lowlevel" that points to "parport_pc", which causes a hang with modprobe -q -- parport_lowlevel blocking forever with a backtrace like this: wait_for_completion_killable+0x1c/0x28 call_usermodehelper_exec+0xa7/0x108 __request_module+0x351/0x3d8 get_lowlevel_driver+0x28/0x41 [parport] __parport_register_driver+0x39/0x1f4 [parport] daisy_drv_init+0x31/0x4f [parport] parport_bus_init+0x5d/0x7b [parport] parport_default_proc_register+0x26/0x1000 [parport] do_one_initcall+0xc2/0x1e0 do_init_module+0x50/0x1d4 load_module+0x1c2e/0x21b3 sys_init_module+0xef/0x117 Supid says: "Due to the new device model daisy driver will now try to find the parallel ports while trying to register its driver so that it can bind with them. Now, since daisy driver is loaded while parport bus is initialising the list of parport is still empty and it tries to load the lowlevel driver, which has an alias set to parport_pc, now causes a deadlock" But I don't think the daisy driver should be loaded by the parport initialization in the first place, so let's revert the whole change. If the daisy driver can just initialize separately on its own (like a driver should), instead of hooking into the parport init sequence directly, this issue probably would go away. Reported-and-bisected-by: Steven Rostedt (VMware) Reported-by: Michal Kubecek Acked-by: Greg Kroah-Hartman Cc: Sudip Mukherjee Signed-off-by: Linus Torvalds --- drivers/parport/daisy.c | 32 +------------------------------- drivers/parport/probe.c | 2 +- drivers/parport/share.c | 10 +--------- include/linux/parport.h | 13 ------------- 4 files changed, 3 insertions(+), 54 deletions(-) diff --git a/drivers/parport/daisy.c b/drivers/parport/daisy.c index 56dd83a45e55d..5484a46dafda8 100644 --- a/drivers/parport/daisy.c +++ b/drivers/parport/daisy.c @@ -213,12 +213,10 @@ void parport_daisy_fini(struct parport *port) struct pardevice *parport_open(int devnum, const char *name) { struct daisydev *p = topology; - struct pardev_cb par_cb; struct parport *port; struct pardevice *dev; int daisy; - memset(&par_cb, 0, sizeof(par_cb)); spin_lock(&topology_lock); while (p && p->devnum != devnum) p = p->next; @@ -232,7 +230,7 @@ struct pardevice *parport_open(int devnum, const char *name) port = parport_get_port(p->port); spin_unlock(&topology_lock); - dev = parport_register_dev_model(port, name, &par_cb, devnum); + dev = parport_register_device(port, name, NULL, NULL, NULL, 0, NULL); parport_put_port(port); if (!dev) return NULL; @@ -482,31 +480,3 @@ static int assign_addrs(struct parport *port) kfree(deviceid); return detected; } - -static int daisy_drv_probe(struct pardevice *par_dev) -{ - struct device_driver *drv = par_dev->dev.driver; - - if (strcmp(drv->name, "daisy_drv")) - return -ENODEV; - if (strcmp(par_dev->name, daisy_dev_name)) - return -ENODEV; - - return 0; -} - -static struct parport_driver daisy_driver = { - .name = "daisy_drv", - .probe = daisy_drv_probe, - .devmodel = true, -}; - -int daisy_drv_init(void) -{ - return parport_register_driver(&daisy_driver); -} - -void daisy_drv_exit(void) -{ - parport_unregister_driver(&daisy_driver); -} diff --git a/drivers/parport/probe.c b/drivers/parport/probe.c index e5e6a463a9412..e035174ba205d 100644 --- a/drivers/parport/probe.c +++ b/drivers/parport/probe.c @@ -257,7 +257,7 @@ static ssize_t parport_read_device_id (struct parport *port, char *buffer, ssize_t parport_device_id (int devnum, char *buffer, size_t count) { ssize_t retval = -ENXIO; - struct pardevice *dev = parport_open(devnum, daisy_dev_name); + struct pardevice *dev = parport_open (devnum, "Device ID probe"); if (!dev) return -ENXIO; diff --git a/drivers/parport/share.c b/drivers/parport/share.c index 0171b8dbcdcd5..5dc53d420ca8c 100644 --- a/drivers/parport/share.c +++ b/drivers/parport/share.c @@ -137,19 +137,11 @@ static struct bus_type parport_bus_type = { int parport_bus_init(void) { - int retval; - - retval = bus_register(&parport_bus_type); - if (retval) - return retval; - daisy_drv_init(); - - return 0; + return bus_register(&parport_bus_type); } void parport_bus_exit(void) { - daisy_drv_exit(); bus_unregister(&parport_bus_type); } diff --git a/include/linux/parport.h b/include/linux/parport.h index f41f1d041e2c5..397607a0c0ebe 100644 --- a/include/linux/parport.h +++ b/include/linux/parport.h @@ -460,7 +460,6 @@ extern size_t parport_ieee1284_epp_read_addr (struct parport *, void *, size_t, int); /* IEEE1284.3 functions */ -#define daisy_dev_name "Device ID probe" extern int parport_daisy_init (struct parport *port); extern void parport_daisy_fini (struct parport *port); extern struct pardevice *parport_open (int devnum, const char *name); @@ -469,18 +468,6 @@ extern ssize_t parport_device_id (int devnum, char *buffer, size_t len); extern void parport_daisy_deselect_all (struct parport *port); extern int parport_daisy_select (struct parport *port, int daisy, int mode); -#ifdef CONFIG_PARPORT_1284 -extern int daisy_drv_init(void); -extern void daisy_drv_exit(void); -#else -static inline int daisy_drv_init(void) -{ - return 0; -} - -static inline void daisy_drv_exit(void) {} -#endif - /* Lowlevel drivers _can_ call this support function to handle irqs. */ static inline void parport_generic_irq(struct parport *port) { -- 2.39.5