diff mbox

[net-next] rhashtable: Do not lower max_elems when max_size is zero

Message ID 20170428061048.GA6817@gondor.apana.org.au
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Herbert Xu April 28, 2017, 6:10 a.m. UTC 
On Thu, Apr 27, 2017 at 03:30:24PM -0700, Florian Fainelli wrote:
> After commit 6d684e54690c ("rhashtable: Cap total number of
> entries to 2^31"), we would be hitting a panic() in net/core/rtnetlink.c
> during initialization. The call stack would look like this:

Thanks for the patch.  I think we could just fold it into the
previous if clause, like this:

---8<---
The commit 6d684e54690c ("rhashtable: Cap total number of entries
to 2^31") breaks rhashtable users that do not set max_size.  This
is because when max_size is zero max_elems is also incorrectly set
to zero instead of 2^31.

This patch fixes it by only lowering max_elems when max_size is not
zero.

Fixes: 6d684e54690c ("rhashtable: Cap total number of entries to 2^31")
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Reported-by: kernel test robot <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Comments

David Miller April 28, 2017, 2:14 p.m. UTC | #1 
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 28 Apr 2017 14:10:48 +0800

> The commit 6d684e54690c ("rhashtable: Cap total number of entries
> to 2^31") breaks rhashtable users that do not set max_size.  This
> is because when max_size is zero max_elems is also incorrectly set
> to zero instead of 2^31.
> 
> This patch fixes it by only lowering max_elems when max_size is not
> zero.
> 
> Fixes: 6d684e54690c ("rhashtable: Cap total number of entries to 2^31")
> Reported-by: Florian Fainelli <f.fainelli@gmail.com>
> Reported-by: kernel test robot <fengguang.wu@intel.com>
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Applied, thanks.
Florian Fainelli April 28, 2017, 3:42 p.m. UTC | #2 
On 04/28/2017 07:14 AM, David Miller wrote:
> From: Herbert Xu <herbert@gondor.apana.org.au>
> Date: Fri, 28 Apr 2017 14:10:48 +0800
> 
>> The commit 6d684e54690c ("rhashtable: Cap total number of entries
>> to 2^31") breaks rhashtable users that do not set max_size.  This
>> is because when max_size is zero max_elems is also incorrectly set
>> to zero instead of 2^31.
>>
>> This patch fixes it by only lowering max_elems when max_size is not
>> zero.
>>
>> Fixes: 6d684e54690c ("rhashtable: Cap total number of entries to 2^31")
>> Reported-by: Florian Fainelli <f.fainelli@gmail.com>
>> Reported-by: kernel test robot <fengguang.wu@intel.com>
>> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Tested-by: Florian Fainelli <f.fainelli@gmail.com>

Thanks Herbert
diff mbox

Patch

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 751630b..3895486 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -958,13 +958,14 @@  int rhashtable_init(struct rhashtable *ht,
 	if (params->min_size)
 		ht->p.min_size = roundup_pow_of_two(params->min_size);
 
-	if (params->max_size)
-		ht->p.max_size = rounddown_pow_of_two(params->max_size);
-
 	/* Cap total entries at 2^31 to avoid nelems overflow. */
 	ht->max_elems = 1u << 31;
-	if (ht->p.max_size < ht->max_elems / 2)
-		ht->max_elems = ht->p.max_size * 2;
+
+	if (params->max_size) {
+		ht->p.max_size = rounddown_pow_of_two(params->max_size);
+		if (ht->p.max_size < ht->max_elems / 2)
+			ht->max_elems = ht->p.max_size * 2;
+	}
 
 	ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE);