pstore: Refactor compression initialization

This refactors compression initialization slightly to better handle
getting potentially called twice (via early pstore_register() calls
and later pstore_init()) and improves the comments and reporting to be
more verbose.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Guenter Roeck <groeck@chromium.org>

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 578f178a695f85dc48013d8d2e600c2ffe2f6dfc..b821054ca3ed3030afcb5a6707643d048713a433 100644 (file)
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -274,36 +274,56 @@ static int pstore_decompress(void *in, void *out,
 
 static void allocate_buf_for_compression(void)
 {
+       struct crypto_comp *ctx;
+       int size;
+       char *buf;
+
+       /* Skip if not built-in or compression backend not selected yet. */
        if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
                return;
 
+       /* Skip if no pstore backend yet or compression init already done. */
+       if (!psinfo || tfm)
+               return;
+
        if (!crypto_has_comp(zbackend->name, 0, 0)) {
-               pr_err("No %s compression\n", zbackend->name);
+               pr_err("Unknown compression: %s\n", zbackend->name);
                return;
        }
 
-       big_oops_buf_sz = zbackend->zbufsize(psinfo->bufsize);
-       if (big_oops_buf_sz <= 0)
+       size = zbackend->zbufsize(psinfo->bufsize);
+       if (size <= 0) {
+               pr_err("Invalid compression size for %s: %d\n",
+                      zbackend->name, size);
                return;
+       }
 
-       big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
-       if (!big_oops_buf) {
-               pr_err("allocate compression buffer error!\n");
+       buf = kmalloc(size, GFP_KERNEL);
+       if (!buf) {
+               pr_err("Failed %d byte compression buffer allocation for: %s\n",
+                      size, zbackend->name);
                return;
        }
 
-       tfm = crypto_alloc_comp(zbackend->name, 0, 0);
-       if (IS_ERR_OR_NULL(tfm)) {
-               kfree(big_oops_buf);
-               big_oops_buf = NULL;
-               pr_err("crypto_alloc_comp() failed!\n");
+       ctx = crypto_alloc_comp(zbackend->name, 0, 0);
+       if (IS_ERR_OR_NULL(ctx)) {
+               kfree(buf);
+               pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
+                      PTR_ERR(ctx));
                return;
        }
+
+       /* A non-NULL big_oops_buf indicates compression is available. */
+       tfm = ctx;
+       big_oops_buf_sz = size;
+       big_oops_buf = buf;
+
+       pr_info("Using compression: %s\n", zbackend->name);
 }
 
 static void free_buf_for_compression(void)
 {
-       if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && !IS_ERR_OR_NULL(tfm))
+       if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm)
                crypto_free_comp(tfm);
        kfree(big_oops_buf);
        big_oops_buf = NULL;
@@ -774,7 +794,6 @@ void __init pstore_choose_compression(void)
        for (step = zbackends; step->name; step++) {
                if (!strcmp(compress, step->name)) {
                        zbackend = step;
-                       pr_info("using %s compression\n", zbackend->name);
                        return;
                }
        }
@@ -791,8 +810,7 @@ static int __init pstore_init(void)
         * initialize compression because crypto was not ready. If so,
         * initialize compression now.
         */
-       if (psinfo && !tfm)
-               allocate_buf_for_compression();
+       allocate_buf_for_compression();
 
        ret = pstore_init_fs();
        if (ret)