All of lore.kernel.org
 help / color / mirror / Atom feed
* crypto: stm32: Broken RPM changes should be reverted
@ 2021-11-27 13:39 Heiner Kallweit
  2021-12-01  6:30 ` crypto: stm32 - Revert broken pm_runtime_resume_and_get changes Herbert Xu
  0 siblings, 1 reply; 4+ messages in thread
From: Heiner Kallweit @ 2021-11-27 13:39 UTC (permalink / raw)
  To: Shixin Liu, Herbert Xu, Rafael J. Wysocki; +Cc: Linux PM

When discussing whether pm_runtime_resume_and_get() should be annotated as
__must_check, I became aware of RPM usage in crypto/stm32.

Following two patches replace usage of pm_runtime_get_sync() with
pm_runtime_resume_and_get() w/o checking the return code.

747bf30fd944 ("crypto: stm32/cryp - Fix PM reference leak on stm32-cryp.c")
1cb3ad701970 ("crypto: stm32/hash - Fix PM reference leak on stm32-hash.c")

This results in RPM usage like the following in stm32_hash_export():

pm_runtime_resume_and_get(hdev->dev);
...
pm_runtime_mark_last_busy(hdev->dev);
pm_runtime_put_autosuspend(hdev->dev);

This is broken. After pm_runtime_resume_and_get() the usage count may be
incremented or not. If not, then the call to pm_runtime_put_autosuspend()
results in exactly the imbalance that the patch claims to fix.

Therefore I think both patches should be reverted, or the return code
of pm_runtime_resume_and_get() has to be checked and properly handled
in the driver logic.

^ permalink raw reply	[flat|nested] 4+ messages in thread
* crypto: stm32 - Revert broken pm_runtime_resume_and_get changes
  2021-11-27 13:39 crypto: stm32: Broken RPM changes should be reverted Heiner Kallweit
@ 2021-12-01  6:30 ` Herbert Xu
  2021-12-01  6:50   ` Heiner Kallweit
  2021-12-01 14:46   ` Rafael J. Wysocki
  0 siblings, 2 replies; 4+ messages in thread
From: Herbert Xu @ 2021-12-01  6:30 UTC (permalink / raw)
  To: Heiner Kallweit
  Cc: Shixin Liu, Rafael J. Wysocki, Linux PM, Linux Crypto Mailing List

On Sat, Nov 27, 2021 at 02:39:52PM +0100, Heiner Kallweit wrote:
> When discussing whether pm_runtime_resume_and_get() should be annotated as
> __must_check, I became aware of RPM usage in crypto/stm32.
> 
> Following two patches replace usage of pm_runtime_get_sync() with
> pm_runtime_resume_and_get() w/o checking the return code.
> 
> 747bf30fd944 ("crypto: stm32/cryp - Fix PM reference leak on stm32-cryp.c")
> 1cb3ad701970 ("crypto: stm32/hash - Fix PM reference leak on stm32-hash.c")
> 
> This results in RPM usage like the following in stm32_hash_export():
> 
> pm_runtime_resume_and_get(hdev->dev);
> ...
> pm_runtime_mark_last_busy(hdev->dev);
> pm_runtime_put_autosuspend(hdev->dev);
> 
> This is broken. After pm_runtime_resume_and_get() the usage count may be
> incremented or not. If not, then the call to pm_runtime_put_autosuspend()
> results in exactly the imbalance that the patch claims to fix.
> 
> Therefore I think both patches should be reverted, or the return code
> of pm_runtime_resume_and_get() has to be checked and properly handled
> in the driver logic.

I agree.  But we can't revert them completely because it does
fix some genuine issues with the ones where we do check the error
code.  What about this patch?

---8<---
We should not call pm_runtime_resume_and_get where the reference
count is expected to be incremented unconditionally.  This patch
reverts these calls to the original unconditional get_sync call.

Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
Fixes: 747bf30fd944 ("crypto: stm32/cryp - Fix PM reference leak...")
Fixes: 1cb3ad701970 ("crypto: stm32/hash - Fix PM reference leak...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/stm32/stm32-cryp.c b/drivers/crypto/stm32/stm32-cryp.c
index 7389a0536ff0..05087831e199 100644
--- a/drivers/crypto/stm32/stm32-cryp.c
+++ b/drivers/crypto/stm32/stm32-cryp.c
@@ -542,7 +542,7 @@ static int stm32_cryp_hw_init(struct stm32_cryp *cryp)
 	int ret;
 	u32 cfg, hw_mode;
 
-	pm_runtime_resume_and_get(cryp->dev);
+	pm_runtime_get_sync(cryp->dev);
 
 	/* Disable interrupt */
 	stm32_cryp_write(cryp, CRYP_IMSCR, 0);
diff --git a/drivers/crypto/stm32/stm32-hash.c b/drivers/crypto/stm32/stm32-hash.c
index 389de9e3302d..d33006d43f76 100644
--- a/drivers/crypto/stm32/stm32-hash.c
+++ b/drivers/crypto/stm32/stm32-hash.c
@@ -813,7 +813,7 @@ static void stm32_hash_finish_req(struct ahash_request *req, int err)
 static int stm32_hash_hw_init(struct stm32_hash_dev *hdev,
 			      struct stm32_hash_request_ctx *rctx)
 {
-	pm_runtime_resume_and_get(hdev->dev);
+	pm_runtime_get_sync(hdev->dev);
 
 	if (!(HASH_FLAGS_INIT & hdev->flags)) {
 		stm32_hash_write(hdev, HASH_CR, HASH_CR_INIT);
@@ -962,7 +962,7 @@ static int stm32_hash_export(struct ahash_request *req, void *out)
 	u32 *preg;
 	unsigned int i;
 
-	pm_runtime_resume_and_get(hdev->dev);
+	pm_runtime_get_sync(hdev->dev);
 
 	while ((stm32_hash_read(hdev, HASH_SR) & HASH_SR_BUSY))
 		cpu_relax();
@@ -1000,7 +1000,7 @@ static int stm32_hash_import(struct ahash_request *req, const void *in)
 
 	preg = rctx->hw_context;
 
-	pm_runtime_resume_and_get(hdev->dev);
+	pm_runtime_get_sync(hdev->dev);
 
 	stm32_hash_write(hdev, HASH_IMR, *preg++);
 	stm32_hash_write(hdev, HASH_STR, *preg++);
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: crypto: stm32 - Revert broken pm_runtime_resume_and_get changes
  2021-12-01  6:30 ` crypto: stm32 - Revert broken pm_runtime_resume_and_get changes Herbert Xu
@ 2021-12-01  6:50   ` Heiner Kallweit
  2021-12-01 14:46   ` Rafael J. Wysocki
  1 sibling, 0 replies; 4+ messages in thread
From: Heiner Kallweit @ 2021-12-01  6:50 UTC (permalink / raw)
  To: Herbert Xu
  Cc: Shixin Liu, Rafael J. Wysocki, Linux PM, Linux Crypto Mailing List

On 01.12.2021 07:30, Herbert Xu wrote:
> On Sat, Nov 27, 2021 at 02:39:52PM +0100, Heiner Kallweit wrote:
>> When discussing whether pm_runtime_resume_and_get() should be annotated as
>> __must_check, I became aware of RPM usage in crypto/stm32.
>>
>> Following two patches replace usage of pm_runtime_get_sync() with
>> pm_runtime_resume_and_get() w/o checking the return code.
>>
>> 747bf30fd944 ("crypto: stm32/cryp - Fix PM reference leak on stm32-cryp.c")
>> 1cb3ad701970 ("crypto: stm32/hash - Fix PM reference leak on stm32-hash.c")
>>
>> This results in RPM usage like the following in stm32_hash_export():
>>
>> pm_runtime_resume_and_get(hdev->dev);
>> ...
>> pm_runtime_mark_last_busy(hdev->dev);
>> pm_runtime_put_autosuspend(hdev->dev);
>>
>> This is broken. After pm_runtime_resume_and_get() the usage count may be
>> incremented or not. If not, then the call to pm_runtime_put_autosuspend()
>> results in exactly the imbalance that the patch claims to fix.
>>
>> Therefore I think both patches should be reverted, or the return code
>> of pm_runtime_resume_and_get() has to be checked and properly handled
>> in the driver logic.
> 
> I agree.  But we can't revert them completely because it does
> fix some genuine issues with the ones where we do check the error
> code.  What about this patch?

Looks good to me, thanks!

> 
> ---8<---
> We should not call pm_runtime_resume_and_get where the reference
> count is expected to be incremented unconditionally.  This patch
> reverts these calls to the original unconditional get_sync call.
> 
> Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
> Fixes: 747bf30fd944 ("crypto: stm32/cryp - Fix PM reference leak...")
> Fixes: 1cb3ad701970 ("crypto: stm32/hash - Fix PM reference leak...")
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
> 
> diff --git a/drivers/crypto/stm32/stm32-cryp.c b/drivers/crypto/stm32/stm32-cryp.c
> index 7389a0536ff0..05087831e199 100644
> --- a/drivers/crypto/stm32/stm32-cryp.c
> +++ b/drivers/crypto/stm32/stm32-cryp.c
> @@ -542,7 +542,7 @@ static int stm32_cryp_hw_init(struct stm32_cryp *cryp)
>  	int ret;
>  	u32 cfg, hw_mode;
>  
> -	pm_runtime_resume_and_get(cryp->dev);
> +	pm_runtime_get_sync(cryp->dev);
>  
>  	/* Disable interrupt */
>  	stm32_cryp_write(cryp, CRYP_IMSCR, 0);
> diff --git a/drivers/crypto/stm32/stm32-hash.c b/drivers/crypto/stm32/stm32-hash.c
> index 389de9e3302d..d33006d43f76 100644
> --- a/drivers/crypto/stm32/stm32-hash.c
> +++ b/drivers/crypto/stm32/stm32-hash.c
> @@ -813,7 +813,7 @@ static void stm32_hash_finish_req(struct ahash_request *req, int err)
>  static int stm32_hash_hw_init(struct stm32_hash_dev *hdev,
>  			      struct stm32_hash_request_ctx *rctx)
>  {
> -	pm_runtime_resume_and_get(hdev->dev);
> +	pm_runtime_get_sync(hdev->dev);
>  
>  	if (!(HASH_FLAGS_INIT & hdev->flags)) {
>  		stm32_hash_write(hdev, HASH_CR, HASH_CR_INIT);
> @@ -962,7 +962,7 @@ static int stm32_hash_export(struct ahash_request *req, void *out)
>  	u32 *preg;
>  	unsigned int i;
>  
> -	pm_runtime_resume_and_get(hdev->dev);
> +	pm_runtime_get_sync(hdev->dev);
>  
>  	while ((stm32_hash_read(hdev, HASH_SR) & HASH_SR_BUSY))
>  		cpu_relax();
> @@ -1000,7 +1000,7 @@ static int stm32_hash_import(struct ahash_request *req, const void *in)
>  
>  	preg = rctx->hw_context;
>  
> -	pm_runtime_resume_and_get(hdev->dev);
> +	pm_runtime_get_sync(hdev->dev);
>  
>  	stm32_hash_write(hdev, HASH_IMR, *preg++);
>  	stm32_hash_write(hdev, HASH_STR, *preg++);
> 


^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: crypto: stm32 - Revert broken pm_runtime_resume_and_get changes
  2021-12-01  6:30 ` crypto: stm32 - Revert broken pm_runtime_resume_and_get changes Herbert Xu
  2021-12-01  6:50   ` Heiner Kallweit
@ 2021-12-01 14:46   ` Rafael J. Wysocki
  1 sibling, 0 replies; 4+ messages in thread
From: Rafael J. Wysocki @ 2021-12-01 14:46 UTC (permalink / raw)
  To: Herbert Xu
  Cc: Heiner Kallweit, Shixin Liu, Rafael J. Wysocki, Linux PM,
	Linux Crypto Mailing List

On Wed, Dec 1, 2021 at 7:30 AM Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Sat, Nov 27, 2021 at 02:39:52PM +0100, Heiner Kallweit wrote:
> > When discussing whether pm_runtime_resume_and_get() should be annotated as
> > __must_check, I became aware of RPM usage in crypto/stm32.
> >
> > Following two patches replace usage of pm_runtime_get_sync() with
> > pm_runtime_resume_and_get() w/o checking the return code.
> >
> > 747bf30fd944 ("crypto: stm32/cryp - Fix PM reference leak on stm32-cryp.c")
> > 1cb3ad701970 ("crypto: stm32/hash - Fix PM reference leak on stm32-hash.c")
> >
> > This results in RPM usage like the following in stm32_hash_export():
> >
> > pm_runtime_resume_and_get(hdev->dev);
> > ...
> > pm_runtime_mark_last_busy(hdev->dev);
> > pm_runtime_put_autosuspend(hdev->dev);
> >
> > This is broken. After pm_runtime_resume_and_get() the usage count may be
> > incremented or not. If not, then the call to pm_runtime_put_autosuspend()
> > results in exactly the imbalance that the patch claims to fix.
> >
> > Therefore I think both patches should be reverted, or the return code
> > of pm_runtime_resume_and_get() has to be checked and properly handled
> > in the driver logic.
>
> I agree.  But we can't revert them completely because it does
> fix some genuine issues with the ones where we do check the error
> code.  What about this patch?
>
> ---8<---
> We should not call pm_runtime_resume_and_get where the reference
> count is expected to be incremented unconditionally.  This patch
> reverts these calls to the original unconditional get_sync call.

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The rule of thumb is to use pm_runtime_resume_and_get() if you want to
check the return value (and act on it) and pm_runtime_get_sync()
otherwise.

> Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
> Fixes: 747bf30fd944 ("crypto: stm32/cryp - Fix PM reference leak...")
> Fixes: 1cb3ad701970 ("crypto: stm32/hash - Fix PM reference leak...")
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>
> diff --git a/drivers/crypto/stm32/stm32-cryp.c b/drivers/crypto/stm32/stm32-cryp.c
> index 7389a0536ff0..05087831e199 100644
> --- a/drivers/crypto/stm32/stm32-cryp.c
> +++ b/drivers/crypto/stm32/stm32-cryp.c
> @@ -542,7 +542,7 @@ static int stm32_cryp_hw_init(struct stm32_cryp *cryp)
>         int ret;
>         u32 cfg, hw_mode;
>
> -       pm_runtime_resume_and_get(cryp->dev);
> +       pm_runtime_get_sync(cryp->dev);
>
>         /* Disable interrupt */
>         stm32_cryp_write(cryp, CRYP_IMSCR, 0);
> diff --git a/drivers/crypto/stm32/stm32-hash.c b/drivers/crypto/stm32/stm32-hash.c
> index 389de9e3302d..d33006d43f76 100644
> --- a/drivers/crypto/stm32/stm32-hash.c
> +++ b/drivers/crypto/stm32/stm32-hash.c
> @@ -813,7 +813,7 @@ static void stm32_hash_finish_req(struct ahash_request *req, int err)
>  static int stm32_hash_hw_init(struct stm32_hash_dev *hdev,
>                               struct stm32_hash_request_ctx *rctx)
>  {
> -       pm_runtime_resume_and_get(hdev->dev);
> +       pm_runtime_get_sync(hdev->dev);
>
>         if (!(HASH_FLAGS_INIT & hdev->flags)) {
>                 stm32_hash_write(hdev, HASH_CR, HASH_CR_INIT);
> @@ -962,7 +962,7 @@ static int stm32_hash_export(struct ahash_request *req, void *out)
>         u32 *preg;
>         unsigned int i;
>
> -       pm_runtime_resume_and_get(hdev->dev);
> +       pm_runtime_get_sync(hdev->dev);
>
>         while ((stm32_hash_read(hdev, HASH_SR) & HASH_SR_BUSY))
>                 cpu_relax();
> @@ -1000,7 +1000,7 @@ static int stm32_hash_import(struct ahash_request *req, const void *in)
>
>         preg = rctx->hw_context;
>
> -       pm_runtime_resume_and_get(hdev->dev);
> +       pm_runtime_get_sync(hdev->dev);
>
>         stm32_hash_write(hdev, HASH_IMR, *preg++);
>         stm32_hash_write(hdev, HASH_STR, *preg++);
> --
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-12-01 14:47 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-11-27 13:39 crypto: stm32: Broken RPM changes should be reverted Heiner Kallweit
2021-12-01  6:30 ` crypto: stm32 - Revert broken pm_runtime_resume_and_get changes Herbert Xu
2021-12-01  6:50   ` Heiner Kallweit
2021-12-01 14:46   ` Rafael J. Wysocki

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.