v2.6.33.5-rc25: initial patch importstart

The goal is to capture the RT work as a linear series of merge-free
standalone commits.  Changes made in merges don't lend themselves to
easy viewing or rebasing onto other versions.  You typically end up
being forced to just generate a giant opaque diff if merges are in play.

In order to have the RT patchset as a linear merge-free set of
commits, we have to start somewhere.   With the benefit of hindsight,
choosing 33-rt25 makes sense since we can immediately nullify the
VFS commits with their corresponding revert.

$ git rev-list  v2.6.33.5-rt25 ^v2.6.33.5 |wc -l
699
$ git rev-list   --no-merges v2.6.33.5-rt25 ^v2.6.33.5 |wc -l
618

Unfortunately you can see there are ~80 merge commits mixed in there.
Even if you assume the most trivial merge conflict, there are still
~100 instances where the 620 commits will fail to apply lurking.
Rewinding deeper into the 33 devel cycle doesn't help, since ~2/3
of them date from 31.

$ git rev-list  --merges v2.6.33-rc8-rt1 ^v2.6.33-rc8|xargs git describe|grep v2
69
$ git rev-list  --merges v2.6.33-rc8-rt1 ^v2.6.33-rc8|xargs git describe|grep v2
29

So, export the 618 raw commits (what you see here) and dive in.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

1 files changed, 175 insertions, 0 deletions

diff --git a/fs-block-preempt-rt-support.patch b/fs-block-preempt-rt-support.patch
new file mode 100644
index 0000000..eeec210
--- /dev/null
+++ b/fs-block-preempt-rt-support.patch
@@ -0,0 +1,175 @@
+From e97977e5171636cba43ae9d30f00cb82e175511b Mon Sep 17 00:00:00 2001
+From: Ingo Molnar <mingo@elte.hu>
+Date: Fri, 3 Jul 2009 08:30:12 -0500
+Subject: [PATCH] fs/block: preempt-rt support
+
+commit e97977e5171636cba43ae9d30f00cb82e175511b in tip.
+
+Signed-off-by: Ingo Molnar <mingo@elte.hu>
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+
+diff --git a/block/blk-core.c b/block/blk-core.c
+index 4b45435..712b29b 100644
+--- a/block/blk-core.c
++++ b/block/blk-core.c
+@@ -201,7 +201,7 @@ EXPORT_SYMBOL(blk_dump_rq_flags);
+  */
+ void blk_plug_device(struct request_queue *q)
+ {
+-	WARN_ON(!irqs_disabled());
++	WARN_ON_NONRT(!irqs_disabled());
+ 
+ 	/*
+ 	 * don't plug a stopped queue, it must be paired with blk_start_queue()
+@@ -241,7 +241,7 @@ EXPORT_SYMBOL(blk_plug_device_unlocked);
+  */
+ int blk_remove_plug(struct request_queue *q)
+ {
+-	WARN_ON(!irqs_disabled());
++	WARN_ON_NONRT(!irqs_disabled());
+ 
+ 	if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q))
+ 		return 0;
+@@ -333,7 +333,7 @@ EXPORT_SYMBOL(blk_unplug);
+  **/
+ void blk_start_queue(struct request_queue *q)
+ {
+-	WARN_ON(!irqs_disabled());
++	WARN_ON_NONRT(!irqs_disabled());
+ 
+ 	queue_flag_clear(QUEUE_FLAG_STOPPED, q);
+ 	__blk_run_queue(q);
+diff --git a/fs/aio.c b/fs/aio.c
+index d065b2c..05e61f7 100644
+--- a/fs/aio.c
++++ b/fs/aio.c
+@@ -612,9 +612,11 @@ static void use_mm(struct mm_struct *mm)
+ 	task_lock(tsk);
+ 	active_mm = tsk->active_mm;
+ 	atomic_inc(&mm->mm_count);
++	local_irq_disable(); // FIXME
++	switch_mm(active_mm, mm, tsk);
+ 	tsk->mm = mm;
+ 	tsk->active_mm = mm;
+-	switch_mm(active_mm, mm, tsk);
++	local_irq_enable();
+ 	task_unlock(tsk);
+ 
+ 	mmdrop(active_mm);
+diff --git a/fs/dcache.c b/fs/dcache.c
+index 9e5cd3c..ce00455 100644
+--- a/fs/dcache.c
++++ b/fs/dcache.c
+@@ -726,8 +726,9 @@ void shrink_dcache_for_umount(struct super_block *sb)
+ {
+ 	struct dentry *dentry;
+ 
+-	if (down_read_trylock(&sb->s_umount))
+-		BUG();
++// -rt: this might succeed there ...
++//	if (down_read_trylock(&sb->s_umount))
++//		BUG();
+ 
+ 	dentry = sb->s_root;
+ 	sb->s_root = NULL;
+diff --git a/fs/exec.c b/fs/exec.c
+index 4a8849e..8d5f4bd 100644
+--- a/fs/exec.c
++++ b/fs/exec.c
+@@ -48,6 +48,7 @@
+ #include <linux/security.h>
+ #include <linux/ima.h>
+ #include <linux/syscalls.h>
++#include <linux/delay.h>
+ #include <linux/tsacct_kern.h>
+ #include <linux/cn_proc.h>
+ #include <linux/audit.h>
+@@ -719,10 +720,12 @@ static int exec_mmap(struct mm_struct *mm)
+ 		}
+ 	}
+ 	task_lock(tsk);
++	local_irq_disable();
+ 	active_mm = tsk->active_mm;
++	activate_mm(active_mm, mm);
+ 	tsk->mm = mm;
+ 	tsk->active_mm = mm;
+-	activate_mm(active_mm, mm);
++	local_irq_enable();
+ 	task_unlock(tsk);
+ 	arch_pick_mmap_layout(mm);
+ 	if (old_mm) {
+diff --git a/fs/file.c b/fs/file.c
+index f313314..710e9b0 100644
+--- a/fs/file.c
++++ b/fs/file.c
+@@ -102,14 +102,15 @@ void free_fdtable_rcu(struct rcu_head *rcu)
+ 		kfree(fdt->open_fds);
+ 		kfree(fdt);
+ 	} else {
+-		fddef = &get_cpu_var(fdtable_defer_list);
++
++		fddef = &per_cpu(fdtable_defer_list, raw_smp_processor_id());
++
+ 		spin_lock(&fddef->lock);
+ 		fdt->next = fddef->next;
+ 		fddef->next = fdt;
+ 		/* vmallocs are handled from the workqueue context */
+ 		schedule_work(&fddef->wq);
+ 		spin_unlock(&fddef->lock);
+-		put_cpu_var(fdtable_defer_list);
+ 	}
+ }
+ 
+diff --git a/fs/pipe.c b/fs/pipe.c
+index 52c4151..7f30ed2 100644
+--- a/fs/pipe.c
++++ b/fs/pipe.c
+@@ -434,8 +434,14 @@ redo:
+ 		wake_up_interruptible_sync(&pipe->wait);
+ 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
+ 	}
++	/*
++	 * Hack: we turn off atime updates for -RT kernels.
++	 * Who uses them on pipes anyway?
++	 */
++#ifndef CONFIG_PREEMPT_RT
+ 	if (ret > 0)
+ 		file_accessed(filp);
++#endif
+ 	return ret;
+ }
+ 
+@@ -607,8 +613,14 @@ out:
+ 		wake_up_interruptible_sync(&pipe->wait);
+ 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+ 	}
++	/*
++	 * Hack: we turn off atime updates for -RT kernels.
++	 * Who uses them on pipes anyway?
++	 */
++#ifndef CONFIG_PREEMPT_RT
+ 	if (ret > 0)
+ 		file_update_time(filp);
++#endif
+ 	return ret;
+ }
+ 
+diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
+index 6f61b7c..dc39a6a 100644
+--- a/fs/proc/task_mmu.c
++++ b/fs/proc/task_mmu.c
+@@ -137,8 +137,10 @@ static void *m_start(struct seq_file *m, loff_t *pos)
+ 	vma = NULL;
+ 	if ((unsigned long)l < mm->map_count) {
+ 		vma = mm->mmap;
+-		while (l-- && vma)
++		while (l-- && vma) {
+ 			vma = vma->vm_next;
++			cond_resched();
++		}
+ 		goto out;
+ 	}
+ 
+-- 
+1.7.1.1
+