[POWERPC] spufs: Add tid file

The new tid file contains the ID of the thread currently running the
context, if any.  This is used so that the new spu-top and spu-ps
tools can find the thread in /proc.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

3 files changed, 32 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index 2e84ed5ae67b..2bb51ca51a6c 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -2039,6 +2039,26 @@ static const struct file_operations spufs_proxydma_info_fops = {
         .read = spufs_proxydma_info_read,
 };
 
+static int spufs_show_tid(struct seq_file *s, void *private)
+{
+        struct spu_context *ctx = s->private;
+
+        seq_printf(s, "%d\n", ctx->tid);
+        return 0;
+}
+
+static int spufs_tid_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, spufs_show_tid, SPUFS_I(inode)->i_ctx);
+}
+
+static const struct file_operations spufs_tid_fops = {
+        .open           = spufs_tid_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
 struct tree_descr spufs_dir_contents[] = {
         { "capabilities", &spufs_caps_fops, 0444, },
         { "mem",  &spufs_mem_fops,  0666, },
@@ -2072,6 +2092,7 @@ struct tree_descr spufs_dir_contents[] = {
         { "wbox_info", &spufs_wbox_info_fops, 0444, },
         { "dma_info", &spufs_dma_info_fops, 0444, },
         { "proxydma_info", &spufs_proxydma_info_fops, 0444, },
+        { "tid", &spufs_tid_fops, 0444, },
         {},
 };
 
@@ -2095,6 +2116,7 @@ struct tree_descr spufs_dir_nosched_contents[] = {
         { "psmap", &spufs_psmap_fops, 0666, },
         { "phys-id", &spufs_id_ops, 0666, },
         { "object-id", &spufs_object_id_ops, 0666, },
+        { "tid", &spufs_tid_fops, 0444, },
         {},
 };
 
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 4381dd00d231..540067550e88 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -102,6 +102,13 @@ void spu_set_timeslice(struct spu_context *ctx)
 void __spu_update_sched_info(struct spu_context *ctx)
 {
         /*
+         * 32-Bit assignment are atomic on powerpc, and we don't care about
+         * memory ordering here because retriving the controlling thread is
+         * per defintion racy.
+         */
+        ctx->tid = current->pid;
+
+        /*
          * We do our own priority calculations, so we normally want
          * ->static_prio to start with. Unfortunately thies field
          * contains junk for threads with a realtime scheduling
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index dab8858b6995..8ff16b4b6bd7 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -77,6 +77,9 @@ struct spu_context {
         struct list_head gang_list;
         struct spu_gang *gang;
 
+        /* owner thread */
+        pid_t tid;
+
         /* scheduler fields */
         struct list_head rq;
         unsigned int time_slice;