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Subject[PATCH 02/15] Remove ctx_info and ctx_info_list
Date
Remove the ctx_info struct entirely, and also the ctx_info_list. This fixes
a race where two processes can clobber each other's ctx_info structs.

Instead of using the list, we just repeat the search through the file
descriptor table.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---
arch/powerpc/platforms/cell/spufs/coredump.c | 79 ++++++-------------------
1 files changed, 19 insertions(+), 60 deletions(-)
diff --git a/arch/powerpc/platforms/cell/spufs/coredump.c b/arch/powerpc/platforms/cell/spufs/coredump.c
index 99f8e0b..6663669 100644
--- a/arch/powerpc/platforms/cell/spufs/coredump.c
+++ b/arch/powerpc/platforms/cell/spufs/coredump.c
@@ -31,15 +31,6 @@

#include "spufs.h"

-struct spufs_ctx_info {
- struct list_head list;
- int dfd;
- int memsize; /* in bytes */
- struct spu_context *ctx;
-};
-
-static LIST_HEAD(ctx_info_list);
-
static ssize_t do_coredump_read(int num, struct spu_context *ctx, void __user *buffer,
size_t size, loff_t *off)
{
@@ -73,25 +64,17 @@ static int spufs_dump_seek(struct file *file, loff_t off)
return 1;
}

-static void spufs_fill_memsize(struct spufs_ctx_info *ctx_info)
+static u64 ctx_ls_size(struct spu_context *ctx)
{
- struct spu_context *ctx;
- unsigned long long lslr;
-
- ctx = ctx_info->ctx;
- lslr = ctx->csa.priv2.spu_lslr_RW;
- ctx_info->memsize = lslr + 1;
+ return ctx->csa.priv2.spu_lslr_RW + 1;
}

-static int spufs_ctx_note_size(struct spufs_ctx_info *ctx_info)
+static int spufs_ctx_note_size(struct spu_context *ctx, int dfd)
{
- int dfd, memsize, i, sz, total = 0;
+ int i, sz, total = 0;
char *name;
char fullname[80];

- dfd = ctx_info->dfd;
- memsize = ctx_info->memsize;
-
for (i = 0; spufs_coredump_read[i].name; i++) {
name = spufs_coredump_read[i].name;
sz = spufs_coredump_read[i].size;
@@ -101,7 +84,7 @@ static int spufs_ctx_note_size(struct spufs_ctx_info *ctx_info)
total += sizeof(struct elf_note);
total += roundup(strlen(fullname) + 1, 4);
if (!strcmp(name, "mem"))
- total += roundup(memsize, 4);
+ total += roundup(ctx_ls_size(ctx), 4);
else
total += roundup(sz, 4);
}
@@ -109,25 +92,6 @@ static int spufs_ctx_note_size(struct spufs_ctx_info *ctx_info)
return total;
}

-static int spufs_add_one_context(struct spu_context *ctx, int dfd)
-{
- struct spufs_ctx_info *ctx_info;
- int size;
-
- ctx_info = kzalloc(sizeof(*ctx_info), GFP_KERNEL);
- if (unlikely(!ctx_info))
- return -ENOMEM;
-
- ctx_info->dfd = dfd;
- ctx_info->ctx = ctx;
-
- spufs_fill_memsize(ctx_info);
-
- size = spufs_ctx_note_size(ctx_info);
- list_add(&ctx_info->list, &ctx_info_list);
- return size;
-}
-
/*
* The additional architecture-specific notes for Cell are various
* context files in the spu context.
@@ -171,7 +135,7 @@ static int spufs_arch_notes_size(void)

fd = 0;
while ((ctx = coredump_next_context(&fd)) != NULL) {
- rc = spufs_add_one_context(ctx, fd);
+ rc = spufs_ctx_note_size(ctx, fd);
if (rc < 0)
break;

@@ -181,12 +145,11 @@ static int spufs_arch_notes_size(void)
return size;
}

-static void spufs_arch_write_note(struct spufs_ctx_info *ctx_info, int i,
- struct file *file)
+static void spufs_arch_write_note(struct spu_context *ctx, int i,
+ struct file *file, int dfd)
{
- struct spu_context *ctx;
loff_t pos = 0;
- int sz, dfd, rc, total = 0;
+ int sz, rc, total = 0;
const int bufsz = PAGE_SIZE;
char *name;
char fullname[80], *buf;
@@ -196,18 +159,13 @@ static void spufs_arch_write_note(struct spufs_ctx_info *ctx_info, int i,
if (!buf)
return;

- dfd = ctx_info->dfd;
name = spufs_coredump_read[i].name;

if (!strcmp(name, "mem"))
- sz = ctx_info->memsize;
+ sz = ctx_ls_size(ctx);
else
sz = spufs_coredump_read[i].size;

- ctx = ctx_info->ctx;
- if (!ctx)
- goto out;
-
sprintf(fullname, "SPU/%d/%s", dfd, name);
en.n_namesz = strlen(fullname) + 1;
en.n_descsz = sz;
@@ -237,16 +195,17 @@ out:

static void spufs_arch_write_notes(struct file *file)
{
- int j;
- struct spufs_ctx_info *ctx_info, *next;
+ struct spu_context *ctx;
+ int fd, j;
+
+ fd = 0;
+ while ((ctx = coredump_next_context(&fd)) != NULL) {
+ spu_acquire_saved(ctx);

- list_for_each_entry_safe(ctx_info, next, &ctx_info_list, list) {
- spu_acquire_saved(ctx_info->ctx);
for (j = 0; j < spufs_coredump_num_notes; j++)
- spufs_arch_write_note(ctx_info, j, file);
- spu_release_saved(ctx_info->ctx);
- list_del(&ctx_info->list);
- kfree(ctx_info);
+ spufs_arch_write_note(ctx, j, file, fd);
+
+ spu_release_saved(ctx);
}
}

--
1.5.1.3.g7a33b
-
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