From c22adc0b0cbe3768619eedc240bf58d88a1d6ed7 Mon Sep 17 00:00:00 2001 From: Xiubo Li Date: Thu, 14 Sep 2017 09:30:05 +0800 Subject: [PATCH] tcmu: fix crash when removing the tcmu device Before the nl REMOVE msg has been sent to the userspace, the ring's and other resources have been released, but the userspace maybe still using them. And then we can see the crash messages like: ring broken, not handling completions BUG: unable to handle kernel paging request at ffffffffffffffd0 IP: tcmu_handle_completions+0x134/0x2f0 [target_core_user] PGD 11bdc0c067 P4D 11bdc0c067 PUD 11bdc0e067 PMD 0 Oops: 0000 [#1] SMP cmd_id not found, ring is broken RIP: 0010:tcmu_handle_completions+0x134/0x2f0 [target_core_user] RSP: 0018:ffffb8a2d8983d88 EFLAGS: 00010296 RAX: 0000000000000000 RBX: ffffb8a2aaa4e000 RCX: 00000000ffffffff RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000220 R10: 0000000076c71401 R11: ffff8d2e76c713f0 R12: ffffb8a2aad56bc0 R13: 000000000000001c R14: ffff8d2e32c90000 R15: ffff8d2e76c713f0 FS: 00007f411ffff700(0000) GS:ffff8d1e7fdc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd0 CR3: 0000001027070000 CR4: 00000000001406e0 Call Trace: ? tcmu_irqcontrol+0x2a/0x40 [target_core_user] ? uio_write+0x7b/0xc0 [uio] ? __vfs_write+0x37/0x150 ? __getnstimeofday64+0x3b/0xd0 ? vfs_write+0xb2/0x1b0 ? syscall_trace_enter+0x1d0/0x2b0 ? SyS_write+0x55/0xc0 ? do_syscall_64+0x67/0x150 ? entry_SYSCALL64_slow_path+0x25/0x25 Code: 41 5d 41 5e 41 5f 5d c3 83 f8 01 0f 85 cf 01 00 00 48 8b 7d d0 e8 dd 5c 1d f3 41 0f b7 74 24 04 48 8b 7d c8 31 d2 e8 5c c7 1b f3 <48> 8b 7d d0 49 89 c7 c6 07 00 0f 1f 40 00 4d 85 ff 0f 84 82 01 RIP: tcmu_handle_completions+0x134/0x2f0 [target_core_user] RSP: ffffb8a2d8983d88 CR2: ffffffffffffffd0 And the crash also could happen in tcmu_page_fault and other places. Signed-off-by: Zhang Zhuoyu Signed-off-by: Xiubo Li Reviewed-by: Mike Christie Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_user.c | 92 ++++++++++++++++++++------------------- 1 file changed, 47 insertions(+), 45 deletions(-) diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c index 942d0942..8b9ec0f 100644 --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -1112,6 +1112,8 @@ static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name) init_waitqueue_head(&udev->nl_cmd_wq); spin_lock_init(&udev->nl_cmd_lock); + INIT_RADIX_TREE(&udev->data_blocks, GFP_KERNEL); + return &udev->se_dev; } @@ -1280,10 +1282,54 @@ static void tcmu_dev_call_rcu(struct rcu_head *p) kfree(udev); } +static int tcmu_check_and_free_pending_cmd(struct tcmu_cmd *cmd) +{ + if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags)) { + kmem_cache_free(tcmu_cmd_cache, cmd); + return 0; + } + return -EINVAL; +} + +static void tcmu_blocks_release(struct tcmu_dev *udev) +{ + int i; + struct page *page; + + /* Try to release all block pages */ + mutex_lock(&udev->cmdr_lock); + for (i = 0; i <= udev->dbi_max; i++) { + page = radix_tree_delete(&udev->data_blocks, i); + if (page) { + __free_page(page); + atomic_dec(&global_db_count); + } + } + mutex_unlock(&udev->cmdr_lock); +} + static void tcmu_dev_kref_release(struct kref *kref) { struct tcmu_dev *udev = container_of(kref, struct tcmu_dev, kref); struct se_device *dev = &udev->se_dev; + struct tcmu_cmd *cmd; + bool all_expired = true; + int i; + + vfree(udev->mb_addr); + udev->mb_addr = NULL; + + /* Upper layer should drain all requests before calling this */ + spin_lock_irq(&udev->commands_lock); + idr_for_each_entry(&udev->commands, cmd, i) { + if (tcmu_check_and_free_pending_cmd(cmd) != 0) + all_expired = false; + } + idr_destroy(&udev->commands); + spin_unlock_irq(&udev->commands_lock); + WARN_ON(!all_expired); + + tcmu_blocks_release(udev); call_rcu(&dev->rcu_head, tcmu_dev_call_rcu); } @@ -1476,8 +1522,6 @@ static int tcmu_configure_device(struct se_device *dev) WARN_ON(udev->data_size % PAGE_SIZE); WARN_ON(udev->data_size % DATA_BLOCK_SIZE); - INIT_RADIX_TREE(&udev->data_blocks, GFP_KERNEL); - info->version = __stringify(TCMU_MAILBOX_VERSION); info->mem[0].name = "tcm-user command & data buffer"; @@ -1527,6 +1571,7 @@ err_netlink: uio_unregister_device(&udev->uio_info); err_register: vfree(udev->mb_addr); + udev->mb_addr = NULL; err_vzalloc: kfree(info->name); info->name = NULL; @@ -1534,37 +1579,11 @@ err_vzalloc: return ret; } -static int tcmu_check_and_free_pending_cmd(struct tcmu_cmd *cmd) -{ - if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags)) { - kmem_cache_free(tcmu_cmd_cache, cmd); - return 0; - } - return -EINVAL; -} - static bool tcmu_dev_configured(struct tcmu_dev *udev) { return udev->uio_info.uio_dev ? true : false; } -static void tcmu_blocks_release(struct tcmu_dev *udev) -{ - int i; - struct page *page; - - /* Try to release all block pages */ - mutex_lock(&udev->cmdr_lock); - for (i = 0; i <= udev->dbi_max; i++) { - page = radix_tree_delete(&udev->data_blocks, i); - if (page) { - __free_page(page); - atomic_dec(&global_db_count); - } - } - mutex_unlock(&udev->cmdr_lock); -} - static void tcmu_free_device(struct se_device *dev) { struct tcmu_dev *udev = TCMU_DEV(dev); @@ -1576,9 +1595,6 @@ static void tcmu_free_device(struct se_device *dev) static void tcmu_destroy_device(struct se_device *dev) { struct tcmu_dev *udev = TCMU_DEV(dev); - struct tcmu_cmd *cmd; - bool all_expired = true; - int i; del_timer_sync(&udev->timeout); @@ -1586,20 +1602,6 @@ static void tcmu_destroy_device(struct se_device *dev) list_del(&udev->node); mutex_unlock(&root_udev_mutex); - vfree(udev->mb_addr); - - /* Upper layer should drain all requests before calling this */ - spin_lock_irq(&udev->commands_lock); - idr_for_each_entry(&udev->commands, cmd, i) { - if (tcmu_check_and_free_pending_cmd(cmd) != 0) - all_expired = false; - } - idr_destroy(&udev->commands); - spin_unlock_irq(&udev->commands_lock); - WARN_ON(!all_expired); - - tcmu_blocks_release(udev); - tcmu_netlink_event(udev, TCMU_CMD_REMOVED_DEVICE, 0, NULL); uio_unregister_device(&udev->uio_info); -- 2.7.4