[POWERPC] spufs: Handle errors in SPU coredump code, and support coredump to a pipe

Rework spufs_coredump_extra_notes_write() to check for and return errors.

If we're coredumping to a pipe we can't trust file->f_pos, we need to
maintain the foffset value passed to us. The cleanest way to do this is
to have the low level write routine increment foffset when we've
successfully written.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

3 files changed, 66 insertions, 33 deletions

diff --git a/arch/powerpc/platforms/cell/spu_syscalls.c b/arch/powerpc/platforms/cell/spu_syscalls.c
index b0117a7c610..a9438b719fe 100644
--- a/arch/powerpc/platforms/cell/spu_syscalls.c
+++ b/arch/powerpc/platforms/cell/spu_syscalls.c
@@ -132,19 +132,17 @@ int elf_coredump_extra_notes_size(void)
 int elf_coredump_extra_notes_write(struct file *file, loff_t *foffset)
 {
         struct spufs_calls *calls;
+        int ret;
 
         calls = spufs_calls_get();
         if (!calls)
                 return 0;
 
-        calls->coredump_extra_notes_write(file);
+        ret = calls->coredump_extra_notes_write(file, foffset);
 
         spufs_calls_put(calls);
 
-        /* Fudge foffset for now */
-        *foffset = file->f_pos;
-
-        return 0;
+        return ret;
 }
 
 int register_spu_syscalls(struct spufs_calls *calls)
diff --git a/arch/powerpc/platforms/cell/spufs/coredump.c b/arch/powerpc/platforms/cell/spufs/coredump.c
index 6c20e44dba6..6b8aef6d7e6 100644
--- a/arch/powerpc/platforms/cell/spufs/coredump.c
+++ b/arch/powerpc/platforms/cell/spufs/coredump.c
@@ -51,19 +51,34 @@ static ssize_t do_coredump_read(int num, struct spu_context *ctx, void *buffer,
  * These are the only things you should do on a core-file: use only these
  * functions to write out all the necessary info.
  */
-static int spufs_dump_write(struct file *file, const void *addr, int nr)
+static int spufs_dump_write(struct file *file, const void *addr, int nr, loff_t *foffset)
 {
-        return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
+        ssize_t written;
+
+        written = file->f_op->write(file, addr, nr, &file->f_pos);
+        *foffset += written;
+
+        if (written != nr)
+                return -EIO;
+
+        return 0;
 }
 
-static int spufs_dump_seek(struct file *file, loff_t off)
+static int spufs_dump_align(struct file *file, char *buf, loff_t new_off,
+                            loff_t *foffset)
 {
-        if (file->f_op->llseek) {
-                if (file->f_op->llseek(file, off, 0) != off)
-                        return 0;
-        } else
-                file->f_pos = off;
-        return 1;
+        int rc, size;
+
+        size = min((loff_t)PAGE_SIZE, new_off - *foffset);
+        memset(buf, 0, size);
+
+        rc = 0;
+        while (rc == 0 && new_off > *foffset) {
+                size = min((loff_t)PAGE_SIZE, new_off - *foffset);
+                rc = spufs_dump_write(file, buf, size, foffset);
+        }
+
+        return rc;
 }
 
 static int spufs_ctx_note_size(struct spu_context *ctx, int dfd)
@@ -141,11 +156,11 @@ int spufs_coredump_extra_notes_size(void)
         return size;
 }
 
-static void spufs_arch_write_note(struct spu_context *ctx, int i,
-                                struct file *file, int dfd)
+static int spufs_arch_write_note(struct spu_context *ctx, int i,
+                                  struct file *file, int dfd, loff_t *foffset)
 {
         loff_t pos = 0;
-        int sz, rc, total = 0;
+        int sz, rc, nread, total = 0;
         const int bufsz = PAGE_SIZE;
         char *name;
         char fullname[80], *buf;
@@ -153,7 +168,7 @@ static void spufs_arch_write_note(struct spu_context *ctx, int i,
 
         buf = (void *)get_zeroed_page(GFP_KERNEL);
         if (!buf)
-                return;
+                return -ENOMEM;
 
         name = spufs_coredump_read[i].name;
         sz = spufs_coredump_read[i].size;
@@ -163,40 +178,60 @@ static void spufs_arch_write_note(struct spu_context *ctx, int i,
         en.n_descsz = sz;
         en.n_type = NT_SPU;
 
-        if (!spufs_dump_write(file, &en, sizeof(en)))
+        rc = spufs_dump_write(file, &en, sizeof(en), foffset);
+        if (rc)
                 goto out;
-        if (!spufs_dump_write(file, fullname, en.n_namesz))
+
+        rc = spufs_dump_write(file, fullname, en.n_namesz, foffset);
+        if (rc)
                 goto out;
-        if (!spufs_dump_seek(file, roundup((unsigned long)file->f_pos, 4)))
+
+        rc = spufs_dump_align(file, buf, roundup(*foffset, 4), foffset);
+        if (rc)
                 goto out;
 
         do {
-                rc = do_coredump_read(i, ctx, buf, bufsz, &pos);
-                if (rc > 0) {
-                        if (!spufs_dump_write(file, buf, rc))
+                nread = do_coredump_read(i, ctx, buf, bufsz, &pos);
+                if (nread > 0) {
+                        rc = spufs_dump_write(file, buf, nread, foffset);
+                        if (rc)
                                 goto out;
-                        total += rc;
+                        total += nread;
                 }
-        } while (rc == bufsz && total < sz);
+        } while (nread == bufsz && total < sz);
+
+        if (nread < 0) {
+                rc = nread;
+                goto out;
+        }
+
+        rc = spufs_dump_align(file, buf, roundup(*foffset - total + sz, 4),
+                              foffset);
 
-        spufs_dump_seek(file, roundup((unsigned long)file->f_pos
-                                                - total + sz, 4));
 out:
         free_page((unsigned long)buf);
+        return rc;
 }
 
-void spufs_coredump_extra_notes_write(struct file *file)
+int spufs_coredump_extra_notes_write(struct file *file, loff_t *foffset)
 {
         struct spu_context *ctx;
-        int fd, j;
+        int fd, j, rc;
 
         fd = 0;
         while ((ctx = coredump_next_context(&fd)) != NULL) {
                 spu_acquire_saved(ctx);
 
-                for (j = 0; spufs_coredump_read[j].name != NULL; j++)
-                        spufs_arch_write_note(ctx, j, file, fd);
+                for (j = 0; spufs_coredump_read[j].name != NULL; j++) {
+                        rc = spufs_arch_write_note(ctx, j, file, fd, foffset);
+                        if (rc) {
+                                spu_release_saved(ctx);
+                                return rc;
+                        }
+                }
 
                 spu_release_saved(ctx);
         }
+
+        return 0;
 }
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index c7b4e035de4..ca47b991bda 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -206,7 +206,7 @@ long spufs_create(struct nameidata *nd, unsigned int flags,
                         mode_t mode, struct file *filp);
 /* ELF coredump callbacks for writing SPU ELF notes */
 extern int spufs_coredump_extra_notes_size(void);
-extern void spufs_coredump_extra_notes_write(struct file *file);
+extern int spufs_coredump_extra_notes_write(struct file *file, loff_t *foffset);
 
 extern const struct file_operations spufs_context_fops;