The patch titled
vt: rework the console spawning variables
has been added to the -mm tree. Its filename is
vt-rework-the-console-spawning-variables.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: vt: rework the console spawning variables
From: ebiederm@xxxxxxxxxxxx (Eric W. Biederman)
This is such a rare path it took me a while to figure out how to test
this after soring out the locking.
This patch does several things.
- The variables used are moved into a structure and declared in vt_kern.h
- A spinlock is added so we don't have SMP races updating the values.
- Instead of raw pid_t value a struct_pid is used to guard against
pid wrap around issues, if the daemon to spawn a new console dies.
Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/char/keyboard.c | 16 ++++++++++++----
drivers/char/vt_ioctl.c | 9 ++++++---
include/linux/vt_kern.h | 7 +++++++
3 files changed, 25 insertions(+), 7 deletions(-)
diff -puN drivers/char/keyboard.c~vt-rework-the-console-spawning-variables drivers/char/keyboard.c
--- a/drivers/char/keyboard.c~vt-rework-the-console-spawning-variables
+++ a/drivers/char/keyboard.c
@@ -108,7 +108,11 @@ const int NR_TYPES = ARRAY_SIZE(max_vals
struct kbd_struct kbd_table[MAX_NR_CONSOLES];
static struct kbd_struct *kbd = kbd_table;
-int spawnpid, spawnsig;
+struct vt_spawn_console vt_spawn_con = {
+ .lock = SPIN_LOCK_UNLOCKED,
+ .pid = NULL,
+ .sig = 0,
+};
/*
* Variables exported for vt.c
@@ -578,9 +582,13 @@ static void fn_compose(struct vc_data *v
static void fn_spawn_con(struct vc_data *vc, struct pt_regs *regs)
{
- if (spawnpid)
- if (kill_proc(spawnpid, spawnsig, 1))
- spawnpid = 0;
+ spin_lock(&vt_spawn_con.lock);
+ if (vt_spawn_con.pid)
+ if (kill_pid(vt_spawn_con.pid, vt_spawn_con.sig, 1)) {
+ put_pid(vt_spawn_con.pid);
+ vt_spawn_con.pid = NULL;
+ }
+ spin_unlock(&vt_spawn_con.lock);
}
static void fn_SAK(struct vc_data *vc, struct pt_regs *regs)
diff -puN drivers/char/vt_ioctl.c~vt-rework-the-console-spawning-variables drivers/char/vt_ioctl.c
--- a/drivers/char/vt_ioctl.c~vt-rework-the-console-spawning-variables
+++ a/drivers/char/vt_ioctl.c
@@ -645,13 +645,16 @@ int vt_ioctl(struct tty_struct *tty, str
*/
case KDSIGACCEPT:
{
- extern int spawnpid, spawnsig;
if (!perm || !capable(CAP_KILL))
return -EPERM;
if (!valid_signal(arg) || arg < 1 || arg == SIGKILL)
return -EINVAL;
- spawnpid = current->pid;
- spawnsig = arg;
+
+ spin_lock_irq(&vt_spawn_con.lock);
+ put_pid(vt_spawn_con.pid);
+ vt_spawn_con.pid = get_pid(task_pid(current));
+ vt_spawn_con.sig = arg;
+ spin_unlock_irq(&vt_spawn_con.lock);
return 0;
}
diff -puN include/linux/vt_kern.h~vt-rework-the-console-spawning-variables include/linux/vt_kern.h
--- a/include/linux/vt_kern.h~vt-rework-the-console-spawning-variables
+++ a/include/linux/vt_kern.h
@@ -84,4 +84,11 @@ void reset_vc(struct vc_data *vc);
extern char con_buf[CON_BUF_SIZE];
extern struct semaphore con_buf_sem;
+struct vt_spawn_console {
+ spinlock_t lock;
+ struct pid *pid;
+ int sig;
+};
+extern struct vt_spawn_console vt_spawn_con;
+
#endif /* _VT_KERN_H */
_
Patches currently in -mm which might be from ebiederm@xxxxxxxxxxxx are
megaraid-use-the-proper-type-to-hold-the-irq-number.patch
x86-put-note-sections-into-a-pt_note-segment-in-vmlinux.patch
msi-use-kmem_cache_zalloc.patch
sysctl-allow-proc-sys-without-sys_sysctl.patch
sysctl-allow-proc-sys-without-sys_sysctl-fix.patch
sysctl-document-that-sys_sysctl-will-be-removed.patch
pid-implement-transfer_pid-and-use-it-to-simplify-de_thread.patch
pid-remove-temporary-debug-code-in-attach_pid.patch
de_thread-use-tsk-not-current.patch
fix-conflict-with-the-is_init-identifier-on-parisc.patch
pidspace-is_init.patch
simplify-update_times-avoid-jiffies-jiffies_64-aliasing-problem-2.patch
kexec-warning-fix.patch
kill-extraneous-printk-in-kernel_restart.patch
fix-mem_write-return-value.patch
kcore-elf-note-namesz-field-fix.patch
stack-overflow-safe-kdump-safe_smp_processor_id.patch
stack-overflow-safe-kdump-safe_smp_processor_id_voyager.patch
stack-overflow-safe-kdump-crash_use_safe_smp_processor_id.patch
stack-overflow-safe-kdump-crash_use_safe_smp_processor_id-fix.patch
stack-overflow-safe-kdump-safe_smp_send_nmi_allbutself.patch
proc-readdir-race-fix-take-3.patch
proc-readdir-race-fix-take-3-race-fix.patch
proc-reorder-the-functions-in-basec.patch
proc-modify-proc_pident_lookup-to-be-completely-table-driven.patch
proc-give-the-root-directory-a-task.patch
pid-implement-access-helpers-for-a-tacks-various-process-groups.patch
pid-add-do_each_pid_task.patch
pid-implement-signal-functions-that-take-a-struct-pid.patch
pid-export-the-symbols-needed-to-use-struct-pid.patch
pid-implement-pid_nr.patch
vt-rework-the-console-spawning-variables.patch
vt-make-vt_pid-a-struct-pid-making-it-pid-wrap-around-safe.patch
vt-update-spawnpid-to-be-a-struct-pid_t.patch
vt-update-spawnpid-to-be-a-struct-pid_t-tidy.patch
file-modify-struct-fown_struct-to-use-a-struct-pid.patch
file-modify-struct-fown_struct-to-use-a-struct-pid-fix.patch
pids-coding-style-use-struct-pidmap.patch
proc-readdir-race-fix-take-3-fix-1.patch
simplify-pid-iterators.patch
move-pidmap-to-pspaceh.patch
move-pidmap-to-pspaceh-fix.patch
define-struct-pspace.patch
proc-readdir-race-fix-take-3-fix-2.patch
update-mq_notify-to-use-a-struct-pid.patch
file-add-locking-to-f_getown.patch
usb-fixup-usb-so-it-uses-struct-pid.patch
proc-sysctl-add-_proc_do_string-helper.patch
namespaces-add-nsproxy.patch
namespaces-add-nsproxy-move-init_nsproxy-into-kernel-nsproxyc.patch
namespaces-incorporate-fs-namespace-into-nsproxy.patch
namespaces-incorporate-fs-namespace-into-nsproxy-whitespace.patch
namespaces-utsname-introduce-temporary-helpers.patch
namespaces-utsname-switch-to-using-uts-namespaces.patch
namespaces-utsname-use-init_utsname-when-appropriate.patch
namespaces-utsname-implement-utsname-namespaces.patch
namespaces-utsname-sysctl-hack.patch
namespaces-utsname-remove-system_utsname.patch
namespaces-utsname-implement-clone_newuts-flag.patch
uts-copy-nsproxy-only-when-needed.patch
namespaces-utsname-switch-to-using-uts-namespaces-klibc-bit.patch
namespaces-utsname-use-init_utsname-when-appropriate-klibc-bit.patch
namespaces-utsname-switch-to-using-uts-namespaces-klibc-bit-2.patch
ipc-namespace-core.patch
ipc-namespace-utils.patch
proc-make-the-generation-of-the-self-symlink-table-driven.patch
proc-factor-out-an-instantiate-method-from-every-lookup-method.patch
proc-remove-the-hard-coded-inode-numbers.patch
proc-merge-proc_tid_attr-and-proc_tgid_attr.patch
proc-use-pid_task-instead-of-open-coding-it.patch
proc-convert-task_sig-to-use-lock_task_sighand.patch
proc-convert-do_task_stat-to-use-lock_task_sighand.patch
proc-drop-tasklist-lock-in-task_state.patch
proc-properly-compute-tgid_offset.patch
proc-remove-trailing-blank-entry-from-pid_entry-arrays.patch
proc-remove-the-useless-smp-safe-comments-from-proc.patch
proc-comment-what-proc_fill_cache-does.patch
genirq-irq-convert-the-move_irq-flag-from-a-32bit-word-to-a-single-bit.patch
genirq-irq-add-moved_masked_irq.patch
genirq-x86_64-irq-reenable-migrating-irqs-to-other-cpus.patch
genirq-msi-simplify-msi-enable-and-disable.patch
genirq-msi-make-the-msi-boolean-tests-return-either-0-or-1.patch
genirq-msi-implement-helper-functions-read_msi_msg-and-write_msi_msg.patch
genirq-msi-refactor-the-msi_ops.patch
genirq-msi-simplify-the-msi-irq-limit-policy.patch
genirq-irq-add-a-dynamic-irq-creation-api.patch
genirq-ia64-irq-dynamic-irq-support.patch
genirq-i386-irq-dynamic-irq-support.patch
genirq-x86_64-irq-dynamic-irq-support.patch
genirq-msi-make-the-msi-code-irq-based-and-not-vector-based.patch
genirq-x86_64-irq-move-msi-message-composition-into-io_apicc.patch
genirq-i386-irq-move-msi-message-composition-into-io_apicc.patch
genirq-msi-only-build-msi-apicc-on-ia64.patch
genirq-msi-only-build-msi-apicc-on-ia64-fix.patch
genirq-x86_64-irq-remove-the-msi-assumption-that-irq-==-vector.patch
genirq-i386-irq-remove-the-msi-assumption-that-irq-==-vector.patch
genirq-irq-remove-msi-hacks.patch
genirq-irq-generalize-the-check-for-hardirq_bits.patch
genirq-x86_64-irq-make-the-external-irq-handlers-report-their-vector-not-the-irq-number.patch
genirq-x86_64-irq-make-vector_irq-per-cpu.patch
genirq-x86_64-irq-make-vector_irq-per-cpu-fix.patch
genirq-x86_64-irq-make-vector_irq-per-cpu-warning-fix.patch
genirq-x86_64-irq-kill-gsi_irq_sharing.patch
genirq-x86_64-irq-kill-irq-compression.patch
add-hypertransport-capability-defines.patch
add-hypertransport-capability-defines-fix.patch
initial-generic-hypertransport-interrupt-support.patch
initial-generic-hypertransport-interrupt-support-Kconfig-fix.patch
pidhash-temporary-debug-checks.patch
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