Re: [PATCH] pstore: Refactor compression initialization

2018-10-18 Thread Kees Cook 
On Thu, Oct 18, 2018 at 10:14 AM, Joe Perches  wrote:
> On Wed, 2018-10-17 at 14:41 -0700, Kees Cook wrote:
>> With compression initialization now separated from pstore_register(),
>> there is no longer a good reason to do compression method selection
>> during fs init. Instead, merge everything together into the late init.
>> Additionally cleans up the reporting to be more clear.
> []
>> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> []
>> @@ -274,36 +274,56 @@ static int pstore_decompress(void *in, void *out,
> []
>> - 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);
>
> Given that there is a generic OOM message emitted on
> kmalloc failures, rather than expanding the unnecessary
> alloc failure message, how about just deleting it instead?

I prefer including more context (i.e. the desired compression method).

-Kees

-- 
Kees Cook
Pixel Security

Re: [PATCH] pstore: Refactor compression initialization

2018-10-18 Thread Joe Perches 
On Wed, 2018-10-17 at 14:41 -0700, Kees Cook wrote:
> With compression initialization now separated from pstore_register(),
> there is no longer a good reason to do compression method selection
> during fs init. Instead, merge everything together into the late init.
> Additionally cleans up the reporting to be more clear.
[]
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
[]
> @@ -274,36 +274,56 @@ static int pstore_decompress(void *in, void *out,
[]
> - 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);

Given that there is a generic OOM message emitted on
kmalloc failures, rather than expanding the unnecessary
alloc failure message, how about just deleting it instead?

Re: [PATCH] pstore: Refactor compression initialization

2018-10-17 Thread Kees Cook 
On Wed, Oct 17, 2018 at 9:42 PM, Sai Prakash Ranjan
 wrote:
> On 10/18/2018 7:00 AM, Joel Fernandes wrote:
> On Wed, Oct 17, 2018 at 02:41:24PM -0700, Kees Cook wrote:
>>>
>>> With compression initialization now separated from pstore_register(),
>>> there is no longer a good reason to do compression method selection
>>> during fs init. Instead, merge everything together into the late init.
>>> Additionally cleans up the reporting to be more clear.
>>>
>>> Signed-off-by: Kees Cook 
>>> ---
>>> This patch goes on top of Joel's. I'll have both in linux-next shortly...
>>> ---
>>>   fs/pstore/inode.c|  2 --
>>>   fs/pstore/internal.h |  3 --
>>>   fs/pstore/platform.c | 65 
>>>   3 files changed, 41 insertions(+), 29 deletions(-)
>>>
>>> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
>>> index 5fcb845b9fec..d814723fb27d 100644
>>> --- a/fs/pstore/inode.c
>>> +++ b/fs/pstore/inode.c
>>> @@ -486,8 +486,6 @@ static int __init init_pstore_fs(void)
>>>   {
>>> int err;
>>>   - pstore_choose_compression();
>>> -
>>> /* Create a convenient mount point for people to access pstore */
>>> err = sysfs_create_mount_point(fs_kobj, "pstore");
>>> if (err)
>>> diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
>>> index fb767e28aeb2..c029314478fa 100644
>>> --- a/fs/pstore/internal.h
>>> +++ b/fs/pstore/internal.h
>>> @@ -37,7 +37,4 @@ extern bool   pstore_is_mounted(void);
>>>   extern void   pstore_record_init(struct pstore_record *record,
>>>struct pstore_info *psi);
>>>   -/* Called during module_init() */
>>> -extern void __init pstore_choose_compression(void);
>>> -
>>>   #endif
>>> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
>>> index f09066db2d4d..e4737a5fa68c 100644
>>> --- 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;
>>> @@ -764,31 +784,28 @@ static void pstore_timefunc(struct timer_list
>>> *unused)
>>>   jiffies + msecs_to_jiffies(pstore_update_ms));
>>>   }
>>>   -void __init pstore_choose_compression(void)
>>> +static int __init pstore_compression_late_init(void)
>>>   {
>>> const struct pstore_zbackend *step;
>>> if (!compress)
>>> -   return;
>>> +   return 0;
>>>   + /* Locate desir

Re: [PATCH] pstore: Refactor compression initialization

2018-10-17 Thread Kees Cook 
On Wed, Oct 17, 2018 at 6:30 PM, Joel Fernandes  wrote:
> On Wed, Oct 17, 2018 at 02:41:24PM -0700, Kees Cook wrote:
>> With compression initialization now separated from pstore_register(),
>> there is no longer a good reason to do compression method selection
>> during fs init. Instead, merge everything together into the late init.
>> Additionally cleans up the reporting to be more clear.
>>
>> Signed-off-by: Kees Cook 
>> ---
>> This patch goes on top of Joel's. I'll have both in linux-next shortly...
>> ---
>>  fs/pstore/inode.c|  2 --
>>  fs/pstore/internal.h |  3 --
>>  fs/pstore/platform.c | 65 
>>  3 files changed, 41 insertions(+), 29 deletions(-)
>>
>> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
>> index 5fcb845b9fec..d814723fb27d 100644
>> --- a/fs/pstore/inode.c
>> +++ b/fs/pstore/inode.c
>> @@ -486,8 +486,6 @@ static int __init init_pstore_fs(void)
>>  {
>>   int err;
>>
>> - pstore_choose_compression();
>> -
>>   /* Create a convenient mount point for people to access pstore */
>>   err = sysfs_create_mount_point(fs_kobj, "pstore");
>>   if (err)
>> diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
>> index fb767e28aeb2..c029314478fa 100644
>> --- a/fs/pstore/internal.h
>> +++ b/fs/pstore/internal.h
>> @@ -37,7 +37,4 @@ extern bool pstore_is_mounted(void);
>>  extern void  pstore_record_init(struct pstore_record *record,
>>  struct pstore_info *psi);
>>
>> -/* Called during module_init() */
>> -extern void __init pstore_choose_compression(void);
>> -
>>  #endif
>> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
>> index f09066db2d4d..e4737a5fa68c 100644
>> --- 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;
>> @@ -764,31 +784,28 @@ static void pstore_timefunc(struct timer_list *unused)
>> jiffies + msecs_to_jiffies(pstore_update_ms));
>>  }
>>
>> -void __init pstore_choose_compression(void)
>> +static int __init pstore_compression_late_init(void)
>>  {
>>   const struct pstore_zbackend *step;
>>
>>   if (!compress)
>> - return;
>> + return 0;
>>
>> + /* Locate desired compression method. */
>>   for (step = zbackends; step->name; step++) {
>>   if (!strcmp(compress, step->name)) {
>>   zbackend = step;
>> - pr_info("using %s compression\n", zbackend->name);
>> - return;
>> +

Re: [PATCH] pstore: Refactor compression initialization

2018-10-17 Thread Sai Prakash Ranjan 

On 10/18/2018 7:00 AM, Joel Fernandes wrote:
On Wed, Oct 17, 2018 at 02:41:24PM -0700, Kees Cook wrote:

With compression initialization now separated from pstore_register(),
there is no longer a good reason to do compression method selection
during fs init. Instead, merge everything together into the late init.
Additionally cleans up the reporting to be more clear.

Signed-off-by: Kees Cook 
---
This patch goes on top of Joel's. I'll have both in linux-next shortly...
---
  fs/pstore/inode.c|  2 --
  fs/pstore/internal.h |  3 --
  fs/pstore/platform.c | 65 
  3 files changed, 41 insertions(+), 29 deletions(-)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 5fcb845b9fec..d814723fb27d 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -486,8 +486,6 @@ static int __init init_pstore_fs(void)
  {
int err;
  
-	pstore_choose_compression();

-
/* Create a convenient mount point for people to access pstore */
err = sysfs_create_mount_point(fs_kobj, "pstore");
if (err)
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index fb767e28aeb2..c029314478fa 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -37,7 +37,4 @@ extern bool   pstore_is_mounted(void);
  extern void   pstore_record_init(struct pstore_record *record,
   struct pstore_info *psi);
  
-/* Called during module_init() */

-extern void __init pstore_choose_compression(void);
-
  #endif
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index f09066db2d4d..e4737a5fa68c 100644
--- 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;
@@ -764,31 +784,28 @@ static void pstore_timefunc(struct timer_list *unused)
  jiffies + msecs_to_jiffies(pstore_update_ms));
  }
  
-void __init pstore_choose_compression(void)

+static int __init pstore_compression_late_init(void)
  {
const struct pstore_zbackend *step;
  
  	if (!compress)

-   return;
+   return 0;
  
+	/* Locate desired compression method. */

for (step = zbackends; step->name; step++) {
if (!strcmp(compress, step->name)) {
zbackend = step;
-   pr_info("using %s compression\n", zbackend->name);
-   return;
+   break;
}
}
-}
  
-static int __init pstore_compression_late_init(void)

-{
/*
-* Check if any pstore backends registered earlier but did not allocate
-* for compression because crypto was not ready

Re: [PATCH] pstore: Refactor compression initialization

2018-10-17 Thread Joel Fernandes 
On Wed, Oct 17, 2018 at 02:41:24PM -0700, Kees Cook wrote:
> With compression initialization now separated from pstore_register(),
> there is no longer a good reason to do compression method selection
> during fs init. Instead, merge everything together into the late init.
> Additionally cleans up the reporting to be more clear.
> 
> Signed-off-by: Kees Cook 
> ---
> This patch goes on top of Joel's. I'll have both in linux-next shortly...
> ---
>  fs/pstore/inode.c|  2 --
>  fs/pstore/internal.h |  3 --
>  fs/pstore/platform.c | 65 
>  3 files changed, 41 insertions(+), 29 deletions(-)
> 
> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
> index 5fcb845b9fec..d814723fb27d 100644
> --- a/fs/pstore/inode.c
> +++ b/fs/pstore/inode.c
> @@ -486,8 +486,6 @@ static int __init init_pstore_fs(void)
>  {
>   int err;
>  
> - pstore_choose_compression();
> -
>   /* Create a convenient mount point for people to access pstore */
>   err = sysfs_create_mount_point(fs_kobj, "pstore");
>   if (err)
> diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
> index fb767e28aeb2..c029314478fa 100644
> --- a/fs/pstore/internal.h
> +++ b/fs/pstore/internal.h
> @@ -37,7 +37,4 @@ extern bool pstore_is_mounted(void);
>  extern void  pstore_record_init(struct pstore_record *record,
>  struct pstore_info *psi);
>  
> -/* Called during module_init() */
> -extern void __init pstore_choose_compression(void);
> -
>  #endif
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index f09066db2d4d..e4737a5fa68c 100644
> --- 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;
> @@ -764,31 +784,28 @@ static void pstore_timefunc(struct timer_list *unused)
> jiffies + msecs_to_jiffies(pstore_update_ms));
>  }
>  
> -void __init pstore_choose_compression(void)
> +static int __init pstore_compression_late_init(void)
>  {
>   const struct pstore_zbackend *step;
>  
>   if (!compress)
> - return;
> + return 0;
>  
> + /* Locate desired compression method. */
>   for (step = zbackends; step->name; step++) {
>   if (!strcmp(compress, step->name)) {
>   zbackend = step;
> - pr_info("using %s compression\n", zbackend->name);
> - return;
> + break;
>   }
>   }
> -}
>  
> -static int __init pstore_compression_late_init(void)
> -{
>   /*
> -  * Check if any pstore backends registered e

[PATCH] pstore: Refactor compression initialization

2018-10-17 Thread Kees Cook 
With compression initialization now separated from pstore_register(),
there is no longer a good reason to do compression method selection
during fs init. Instead, merge everything together into the late init.
Additionally cleans up the reporting to be more clear.

Signed-off-by: Kees Cook 
---
This patch goes on top of Joel's. I'll have both in linux-next shortly...
---
 fs/pstore/inode.c|  2 --
 fs/pstore/internal.h |  3 --
 fs/pstore/platform.c | 65 
 3 files changed, 41 insertions(+), 29 deletions(-)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 5fcb845b9fec..d814723fb27d 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -486,8 +486,6 @@ static int __init init_pstore_fs(void)
 {
int err;
 
-   pstore_choose_compression();
-
/* Create a convenient mount point for people to access pstore */
err = sysfs_create_mount_point(fs_kobj, "pstore");
if (err)
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index fb767e28aeb2..c029314478fa 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -37,7 +37,4 @@ extern bool   pstore_is_mounted(void);
 extern voidpstore_record_init(struct pstore_record *record,
   struct pstore_info *psi);
 
-/* Called during module_init() */
-extern void __init pstore_choose_compression(void);
-
 #endif
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index f09066db2d4d..e4737a5fa68c 100644
--- 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;
@@ -764,31 +784,28 @@ static void pstore_timefunc(struct timer_list *unused)
  jiffies + msecs_to_jiffies(pstore_update_ms));
 }
 
-void __init pstore_choose_compression(void)
+static int __init pstore_compression_late_init(void)
 {
const struct pstore_zbackend *step;
 
if (!compress)
-   return;
+   return 0;
 
+   /* Locate desired compression method. */
for (step = zbackends; step->name; step++) {
if (!strcmp(compress, step->name)) {
zbackend = step;
-   pr_info("using %s compression\n", zbackend->name);
-   return;
+   break;
}
}
-}
 
-static int __init pstore_compression_late_init(void)
-{
/*
-* Check if any pstore backends registered earlier but did not allocate
-* for compression because crypto was not ready, if so then initialize
-* compression.
+* Check if any pstore backends registered ear