[PATCH] pidspace: is_init()

This is an updated version of Eric Biederman's is_init() patch.
(http://lkml.org/lkml/2006/2/6/280).  It applies cleanly to 2.6.18-rc3 and
replaces a few more instances of ->pid == 1 with is_init().

Further, is_init() checks pid and thus removes dependency on Eric's other
patches for now.

Eric's original description:

	There are a lot of places in the kernel where we test for init
	because we give it special properties.  Most  significantly init
	must not die.  This results in code all over the kernel test
	->pid == 1.

	Introduce is_init to capture this case.

	With multiple pid spaces for all of the cases affected we are
	looking for only the first process on the system, not some other
	process that has pid == 1.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: <lxc-devel@lists.sourceforge.net>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 622dabd846800b14fb13c623eff5c61da0ac9cf7..8871529a34e2026e4f2bd4eda531df7ec59808a4 100644 (file)
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -193,7 +193,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
        /* We ran out of memory, or some other thing happened to us that
           made us unable to handle the page fault gracefully.  */
  out_of_memory:
-       if (current->pid == 1) {
+       if (is_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index a5b33ff3924edc35c216f93232031f802651c4ad..5e658a8744984688ee171e16b67a44aee65c1331 100644 (file)
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -198,7 +198,7 @@ survive:
                return fault;
        }
 
-       if (tsk->pid != 1)
+       if (!is_init(tsk))
                goto out;
 
        /*

diff --git a/arch/arm26/mm/fault.c b/arch/arm26/mm/fault.c
index a7c4cc922095a184f8dc95f85f7332f857f26b12..a1f6d8a9cc32919084d14b5cf9181dbceb013ca6 100644 (file)
--- a/arch/arm26/mm/fault.c
+++ b/arch/arm26/mm/fault.c
@@ -185,7 +185,7 @@ survive:
        }
 
        fault = -3; /* out of memory */
-       if (tsk->pid != 1)
+       if (!is_init(tsk))
                goto out;
 
        /*

diff --git a/arch/i386/lib/usercopy.c b/arch/i386/lib/usercopy.c
index efc7e7d5f4d0f518847b5232f38aad75ea9367f4..08502fc6d0cb8d0fc819682d26b499e5aab08efb 100644 (file)
--- a/arch/i386/lib/usercopy.c
+++ b/arch/i386/lib/usercopy.c
@@ -739,7 +739,7 @@ survive:
                        retval = get_user_pages(current, current->mm,
                                        (unsigned long )to, 1, 1, 0, &pg, NULL);
 
-                       if (retval == -ENOMEM && current->pid == 1) {
+                       if (retval == -ENOMEM && is_init(current)) {
                                up_read(&current->mm->mmap_sem);
                                blk_congestion_wait(WRITE, HZ/50);
                                goto survive;

diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index 50d8617391dd09cfd86bde16882580c9cc8cebb1..2581575786c135a0a0201cf63caf754a8654a755 100644 (file)
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -589,7 +589,7 @@ no_context:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (tsk->pid == 1) {
+       if (is_init(tsk)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index d8b1b4ac7f2609f5a4a1a5294d3721c53baae885..59f3ab937615fb0fbe40ae08061b3aa47a32a775 100644 (file)
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -280,7 +280,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
 
   out_of_memory:
        up_read(&mm->mmap_sem);
-       if (current->pid == 1) {
+       if (is_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c
index dc18a33eefef36ccd10790525b2537e4cae89255..8d5f551b5754305e87474b617b8e437925b48f76 100644 (file)
--- a/arch/m32r/mm/fault.c
+++ b/arch/m32r/mm/fault.c
@@ -299,7 +299,7 @@ no_context:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (tsk->pid == 1) {
+       if (is_init(tsk)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index 5e2d87c10c872bbdf42d4dc6bcce1ccd7b72b579..911f2ce3f53e11ec6d1e0deeba875735d5c2a13b 100644 (file)
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -181,7 +181,7 @@ good_area:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (current->pid == 1) {
+       if (is_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index a4f8c45c4e8ede95a018f85da394317a88153ba4..8423d859077949520de140f5b03d7cfdecda92e1 100644 (file)
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -171,7 +171,7 @@ no_context:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (tsk->pid == 1) {
+       if (is_init(tsk)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 77953f41d75406c200085e0bca8151857df9742f..e8fa50624b70dae41c27ce669e10f472b18970a8 100644 (file)
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -386,7 +386,7 @@ bad_area_nosemaphore:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (current->pid == 1) {
+       if (is_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index 903115d67fdcc5230b718abb6dfb25038881d5b8..311ed1993fc036de995f444bac92d1a327236c89 100644 (file)
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -337,7 +337,7 @@ static int recover_mce(struct pt_regs *regs, struct rtas_error_log * err)
                   err->disposition == RTAS_DISP_NOT_RECOVERED &&
                   err->target == RTAS_TARGET_MEMORY &&
                   err->type == RTAS_TYPE_ECC_UNCORR &&
-                  !(current->pid == 0 || current->pid == 1)) {
+                  !(current->pid == 0 || is_init(current))) {
                /* Kill off a user process with an ECC error */
                printk(KERN_ERR "MCE: uncorrectable ecc error for pid %d\n",
                       current->pid);

diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
index d7a433049b4857b3acf2caa59e6f7c981d1c5f21..aafc8e8893d1ebc0ac969b097f77d9f976d616ee 100644 (file)
--- a/arch/ppc/kernel/traps.c
+++ b/arch/ppc/kernel/traps.c
@@ -119,7 +119,7 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
         * generate the same exception over and over again and we get
         * nowhere.  Better to kill it and let the kernel panic.
         */
-       if (current->pid == 1) {
+       if (is_init(current)) {
                __sighandler_t handler;
 
                spin_lock_irq(&current->sighand->siglock);

diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c
index bc776beb3136f28bced9d3a4ab08d4efc039e5f8..465f451f3bc3a8a95908dcaa4d31757e04bc9f26 100644 (file)
--- a/arch/ppc/mm/fault.c
+++ b/arch/ppc/mm/fault.c
@@ -291,7 +291,7 @@ bad_area:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (current->pid == 1) {
+       if (is_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index f2b9a84dc2bff3e424be20442a1835146c7f2924..9c3c19fe62fcd99dfb3893730d7f54b354b731f5 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -353,7 +353,7 @@ no_context:
 */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (tsk->pid == 1) {
+       if (is_init(tsk)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 507f28914706ba4c8e4768c06df5f79a5bc6f998..68663b8f99aec28619ea7cb92d16978c5a08be25 100644 (file)
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -149,7 +149,7 @@ no_context:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (current->pid == 1) {
+       if (is_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/sh64/mm/fault.c b/arch/sh64/mm/fault.c
index f08d0eaf6497d34c716d8f0c5ee4baf2aa4eb27c..8e2f6c28b7390fc712a8d07f8e8e567fbd7b6853 100644 (file)
--- a/arch/sh64/mm/fault.c
+++ b/arch/sh64/mm/fault.c
@@ -277,7 +277,7 @@ bad_area:
                        show_regs(regs);
 #endif
                }
-               if (tsk->pid == 1) {
+               if (is_init(tsk)) {
                        panic("INIT had user mode bad_area\n");
                }
                tsk->thread.address = address;
@@ -319,14 +319,14 @@ no_context:
  * us unable to handle the page fault gracefully.
  */
 out_of_memory:
-       if (current->pid == 1) {
+       if (is_init(current)) {
                panic("INIT out of memory\n");
                yield();
                goto survive;
        }
        printk("fault:Out of memory\n");
        up_read(&mm->mmap_sem);
-       if (current->pid == 1) {
+       if (is_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 61a23fff4395e822f1ee481a9ab589003201b1ba..c7b195c7e51fa3ddc3d46da245f2f0f5ce7fa6fe 100644 (file)
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -120,7 +120,7 @@ out_nosemaphore:
  * us unable to handle the page fault gracefully.
  */
 out_of_memory:
-       if (current->pid == 1) {
+       if (is_init(current)) {
                up_read(&mm->mmap_sem);
                yield();
                down_read(&mm->mmap_sem);

diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
index 9ba54cc2b5f676e0cfe0ed4a6f6fee53daa7ddeb..3751b4788e288748112c05df0121a1186aac5fab 100644 (file)
--- a/arch/x86_64/mm/fault.c
+++ b/arch/x86_64/mm/fault.c
@@ -244,7 +244,7 @@ static int is_errata93(struct pt_regs *regs, unsigned long address)
 
 int unhandled_signal(struct task_struct *tsk, int sig)
 {
-       if (tsk->pid == 1)
+       if (is_init(tsk))
                return 1;
        if (tsk->ptrace & PT_PTRACED)
                return 0;
@@ -580,7 +580,7 @@ no_context:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (current->pid == 1) { 
+       if (is_init(current)) {
                yield();
                goto again;
        }

diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index a945a33e85a129d0e268b1e20cf9a54710ec93c6..dd0dbec2e57e4f39b51ab7a73359a0117e638b48 100644 (file)
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -144,7 +144,7 @@ bad_area:
         */
 out_of_memory:
        up_read(&mm->mmap_sem);
-       if (current->pid == 1) {
+       if (is_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;

diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index ee3ca8f1768e9be995a62a252404ad4712d5d6bc..0ad6cb081db4d1b3681a7b069d9439454e3bd9fc 100644 (file)
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -208,7 +208,7 @@ static void send_sig_all(int sig)
        struct task_struct *p;
 
        for_each_process(p) {
-               if (p->mm && p->pid != 1)
+               if (p->mm && !is_init(p))
                        /* Not swapper, init nor kernel thread */
                        force_sig(sig, p);
        }

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3696f2f7126d60fb54c907a77b945c846aaaacd0..ed2af86715898b262b25e0ff9e5788ef821f03ae 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1033,6 +1033,16 @@ static inline int pid_alive(struct task_struct *p)
        return p->pids[PIDTYPE_PID].pid != NULL;
 }
 
+/**
+ * is_init - check if a task structure is the first user space
+ *          task the kernel created.
+ * @p: Task structure to be checked.
+ */
+static inline int is_init(struct task_struct *tsk)
+{
+       return tsk->pid == 1;
+}
+
 extern void free_task(struct task_struct *tsk);
 #define get_task_struct(tsk) do { atomic_inc(&(tsk)->usage); } while(0)
 

diff --git a/kernel/capability.c b/kernel/capability.c
index c7685ad00a97c4ddfd2f47029f0b5b4342da80be..edb845a6e84ae5e649ece39e18384620c5dac74e 100644 (file)
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -133,7 +133,7 @@ static inline int cap_set_all(kernel_cap_t *effective,
      int found = 0;
 
      do_each_thread(g, target) {
-             if (target == current || target->pid == 1)
+             if (target == current || is_init(target))
                      continue;
              found = 1;
             if (security_capset_check(target, effective, inheritable,

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1b32c2c04c153a056047134a28ed5f172eeb1f80..584bb4e6c0421cb5e25b5a68f2f694accad4383a 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -240,7 +240,7 @@ static struct super_block *cpuset_sb;
  * A cpuset can only be deleted if both its 'count' of using tasks
  * is zero, and its list of 'children' cpusets is empty.  Since all
  * tasks in the system use _some_ cpuset, and since there is always at
- * least one task in the system (init, pid == 1), therefore, top_cpuset
+ * least one task in the system (init), therefore, top_cpuset
  * always has either children cpusets and/or using tasks.  So we don't
  * need a special hack to ensure that top_cpuset cannot be deleted.
  *

diff --git a/kernel/exit.c b/kernel/exit.c
index 4b6fb054b25d715b906ca60d3b674f1be041d184..9961192d6055ca15fe9da23516755482a20313d7 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -219,7 +219,7 @@ static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
        do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
                if (p == ignored_task
                                || p->exit_state
-                               || p->real_parent->pid == 1)
+                               || is_init(p->real_parent))
                        continue;
                if (process_group(p->real_parent) != pgrp
                            && p->real_parent->signal->session == p->signal->session) {

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 50087ecf337ea17e5429188688187b6623a57f20..37cad75cf49460a6b3cd99d1586b966516e5bc8e 100644 (file)
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -40,7 +40,7 @@ struct resource crashk_res = {
 
 int kexec_should_crash(struct task_struct *p)
 {
-       if (in_interrupt() || !p->pid || p->pid == 1 || panic_on_oops)
+       if (in_interrupt() || !p->pid || is_init(p) || panic_on_oops)
                return 1;
        return 0;
 }

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 8aad0331d82eae17482a37056c0368a8e6274661..4d50e06fd745cf28fc940252d856b51d1b372110 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -440,6 +440,7 @@ struct task_struct *ptrace_get_task_struct(pid_t pid)
        child = find_task_by_pid(pid);
        if (child)
                get_task_struct(child);
+
        read_unlock(&tasklist_lock);
        if (!child)
                return ERR_PTR(-ESRCH);

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8bfa7d117c54fb8ef2b0e5e458caf3303e17b366..9535a38399307130b0a1f5728fbfece8333d3d93 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1915,7 +1915,7 @@ int proc_dointvec_bset(ctl_table *table, int write, struct file *filp,
                return -EPERM;
        }
 
-       op = (current->pid == 1) ? OP_SET : OP_AND;
+       op = is_init(current) ? OP_SET : OP_AND;
        return do_proc_dointvec(table,write,filp,buffer,lenp,ppos,
                                do_proc_dointvec_bset_conv,&op);
 }

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index bada3d03119ff01381d6d47c1b828b59c3867106..f3dd79c1c367c05aa05c16ef6ce557052c1ae8b9 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -255,7 +255,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
  */
 static void __oom_kill_task(struct task_struct *p, const char *message)
 {
-       if (p->pid == 1) {
+       if (is_init(p)) {
                WARN_ON(1);
                printk(KERN_WARNING "tried to kill init!\n");
                return;

diff --git a/security/commoncap.c b/security/commoncap.c
index f50fc298cf801991879bee1de094dd56671562c3..5a5ef5ca7ea97eb9a2ef3901e3faff71fcaefcc6 100644 (file)
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -169,7 +169,7 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
        /* For init, we want to retain the capabilities set
         * in the init_task struct. Thus we skip the usual
         * capability rules */
-       if (current->pid != 1) {
+       if (!is_init(current)) {
                current->cap_permitted = new_permitted;
                current->cap_effective =
                    cap_intersect (new_permitted, bprm->cap_effective);