From: Ian Abbott <[EMAIL PROTECTED]> Stable request for 2.6.24.
This patch works around a problem in the fakephp driver when a process writing "0" to a "power" sysfs file to fake removal of a PCI device ends up deadlocking itself in the sysfs code. The patch was recently accepted into Linus' tree after the 2.6.24 release: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=5c796ae7a7ebe56967ed9b9963d7c16d733635ff Signed-off-by: Ian Abbott <[EMAIL PROTECTED]> --- --- linux-2.6.24/drivers/pci/hotplug/fakephp.c.orig 2008-01-24 22:58:37.000000000 +0000 +++ linux-2.6.24/drivers/pci/hotplug/fakephp.c 2008-01-25 15:58:21.000000000 +0000 @@ -39,6 +39,7 @@ #include <linux/init.h> #include <linux/string.h> #include <linux/slab.h> +#include <linux/workqueue.h> #include "../pci.h" #if !defined(MODULE) @@ -63,10 +64,16 @@ struct dummy_slot { struct list_head node; struct hotplug_slot *slot; struct pci_dev *dev; + struct work_struct remove_work; + unsigned long removed; }; static int debug; static LIST_HEAD(slot_list); +static struct workqueue_struct *dummyphp_wq; + +static void pci_rescan_worker(struct work_struct *work); +static DECLARE_WORK(pci_rescan_work, pci_rescan_worker); static int enable_slot (struct hotplug_slot *slot); static int disable_slot (struct hotplug_slot *slot); @@ -109,7 +116,7 @@ static int add_slot(struct pci_dev *dev) slot->name = &dev->dev.bus_id[0]; dbg("slot->name = %s\n", slot->name); - dslot = kmalloc(sizeof(struct dummy_slot), GFP_KERNEL); + dslot = kzalloc(sizeof(struct dummy_slot), GFP_KERNEL); if (!dslot) goto error_info; @@ -164,6 +171,14 @@ static void remove_slot(struct dummy_slo err("Problem unregistering a slot %s\n", dslot->slot->name); } +/* called from the single-threaded workqueue handler to remove a slot */ +static void remove_slot_worker(struct work_struct *work) +{ + struct dummy_slot *dslot = + container_of(work, struct dummy_slot, remove_work); + remove_slot(dslot); +} + /** * pci_rescan_slot - Rescan slot * @temp: Device template. Should be set: bus and devfn. @@ -267,11 +282,17 @@ static inline void pci_rescan(void) { pci_rescan_buses(&pci_root_buses); } +/* called from the single-threaded workqueue handler to rescan all pci buses */ +static void pci_rescan_worker(struct work_struct *work) +{ + pci_rescan(); +} static int enable_slot(struct hotplug_slot *hotplug_slot) { /* mis-use enable_slot for rescanning of the pci bus */ - pci_rescan(); + cancel_work_sync(&pci_rescan_work); + queue_work(dummyphp_wq, &pci_rescan_work); return -ENODEV; } @@ -306,6 +327,10 @@ static int disable_slot(struct hotplug_s err("Can't remove PCI devices with other PCI devices behind it yet.\n"); return -ENODEV; } + if (test_and_set_bit(0, &dslot->removed)) { + dbg("Slot already scheduled for removal\n"); + return -ENODEV; + } /* search for subfunctions and disable them first */ if (!(dslot->dev->devfn & 7)) { for (func = 1; func < 8; func++) { @@ -328,8 +353,9 @@ static int disable_slot(struct hotplug_s /* remove the device from the pci core */ pci_remove_bus_device(dslot->dev); - /* blow away this sysfs entry and other parts. */ - remove_slot(dslot); + /* queue work item to blow away this sysfs entry and other parts. */ + INIT_WORK(&dslot->remove_work, remove_slot_worker); + queue_work(dummyphp_wq, &dslot->remove_work); return 0; } @@ -340,6 +366,7 @@ static void cleanup_slots (void) struct list_head *next; struct dummy_slot *dslot; + destroy_workqueue(dummyphp_wq); list_for_each_safe (tmp, next, &slot_list) { dslot = list_entry (tmp, struct dummy_slot, node); remove_slot(dslot); @@ -351,6 +378,10 @@ static int __init dummyphp_init(void) { info(DRIVER_DESC "\n"); + dummyphp_wq = create_singlethread_workqueue(MY_NAME); + if (!dummyphp_wq) + return -ENOMEM; + return pci_scan_buses(); } -- -=( Ian Abbott @ MEV Ltd. E-mail: <[EMAIL PROTECTED]> )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
