[PATCH] pacct: none-delayed process accounting accumulation

In current 2.6.17 implementation, signal_struct refered from task_struct is
used for per-process data structure.  The pacct facility also uses it as a
per-process data structure to store stime, utime, minflt, majflt.  But those
members are saved in __exit_signal().  It's too late.

For example, if some threads exits at same time, pacct facility has a
possibility to drop accountings for a part of those threads.  (see, the
following 'The results of original 2.6.17 kernel') I think accounting
information should be completely collected into the per-process data structure
before writing out an accounting record.

This patch fixes this matter.  Accumulation of stime, utime, minflt and majflt
are done before generating accounting record.

[mingo@elte.hu: fix acct_collect() siglock bug found by lockdep]
Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 13 deletions

diff --git a/kernel/acct.c b/kernel/acct.c
index 4c85fdf615da..368c4f03fe0e 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -428,7 +428,6 @@ static void do_acct_process(struct file *file)
         u64 elapsed;
         u64 run_time;
         struct timespec uptime;
-        unsigned long jiffies;
 
         /*
          * First check to see if there is enough free_space to continue
@@ -469,12 +468,6 @@ static void do_acct_process(struct file *file)
 #endif
         do_div(elapsed, AHZ);
         ac.ac_btime = xtime.tv_sec - elapsed;
-        jiffies = cputime_to_jiffies(cputime_add(current->utime,
-                                                 current->signal->utime));
-        ac.ac_utime = encode_comp_t(jiffies_to_AHZ(jiffies));
-        jiffies = cputime_to_jiffies(cputime_add(current->stime,
-                                                 current->signal->stime));
-        ac.ac_stime = encode_comp_t(jiffies_to_AHZ(jiffies));
         /* we really need to bite the bullet and change layout */
         ac.ac_uid = current->uid;
         ac.ac_gid = current->gid;
@@ -497,16 +490,16 @@ static void do_acct_process(struct file *file)
         read_unlock(&tasklist_lock);
 
         spin_lock(&current->sighand->siglock);
+        ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
+        ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
         ac.ac_flag = pacct->ac_flag;
         ac.ac_mem = encode_comp_t(pacct->ac_mem);
+        ac.ac_minflt = encode_comp_t(pacct->ac_minflt);
+        ac.ac_majflt = encode_comp_t(pacct->ac_majflt);
         ac.ac_exitcode = pacct->ac_exitcode;
         spin_unlock(&current->sighand->siglock);
         ac.ac_io = encode_comp_t(0 /* current->io_usage */);    /* %% */
         ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
-        ac.ac_minflt = encode_comp_t(current->signal->min_flt +
-                                     current->min_flt);
-        ac.ac_majflt = encode_comp_t(current->signal->maj_flt +
-                                     current->maj_flt);
         ac.ac_swaps = encode_comp_t(0);
 
         /*
@@ -532,6 +525,7 @@ static void do_acct_process(struct file *file)
 void acct_init_pacct(struct pacct_struct *pacct)
 {
         memset(pacct, 0, sizeof(struct pacct_struct));
+        pacct->ac_utime = pacct->ac_stime = cputime_zero;
 }
 
 /**
@@ -555,7 +549,7 @@ void acct_collect(long exitcode, int group_dead)
                 up_read(&current->mm->mmap_sem);
         }
 
-        spin_lock(&current->sighand->siglock);
+        spin_lock_irq(&current->sighand->siglock);
         if (group_dead)
                 pacct->ac_mem = vsize / 1024;
         if (thread_group_leader(current)) {
@@ -569,7 +563,11 @@ void acct_collect(long exitcode, int group_dead)
                 pacct->ac_flag |= ACORE;
         if (current->flags & PF_SIGNALED)
                 pacct->ac_flag |= AXSIG;
-        spin_unlock(&current->sighand->siglock);
+        pacct->ac_utime = cputime_add(pacct->ac_utime, current->utime);
+        pacct->ac_stime = cputime_add(pacct->ac_stime, current->stime);
+        pacct->ac_minflt += current->min_flt;
+        pacct->ac_majflt += current->maj_flt;
+        spin_unlock_irq(&current->sighand->siglock);
 }
 
 /**