Hi Pablo Thanks for the clarification. I just sent the patch using "git send-email". Probably that will show up as different mail thread.
Thanks Dhana On Wed, Mar 2, 2016 at 9:22 AM, De Lara Guarch, Pablo < pablo.de.lara.guarch at intel.com> wrote: > Hi Dhana, > > > -----Original Message----- > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Dhananjaya Reddy > > Eadala > > Sent: Wednesday, March 02, 2016 2:02 PM > > To: Qiu, Michael > > Cc: dev at dpdk.org > > Subject: Re: [dpdk-dev] [PATCH] hash: fix memcmp function pointer in > multi- > > process > > > > Michael > > > > Please find the attached is the patch file generated from "git > format-patch > > -1" > > What Michael means is that you should use git send-email and not attach > the patch > to the mail. > > You can use: > > git send-email -1 --to dev at dpdk.org > > or > > git send-email your-patch.patch --to dev at dpdk.org > > Take a look at dpdk.org/dev for more details and how to configure git > with your smtp server details. > > Thanks, > Pablo > > > > > > > Thanks > > Dhana > > > > > > On Tue, Mar 1, 2016 at 9:29 PM, Qiu, Michael <michael.qiu at intel.com> > > wrote: > > > > > On 3/2/2016 2:57 AM, Dhananjaya Reddy Eadala wrote: > > > > Hi > > > > > > > > We found a problem in dpdk-2.2 using under multi-process environment. > > > > Here is the brief description how we are using the dpdk: > > > > > > > > We have two processes proc1, proc2 using dpdk. These proc1 and proc2 > > are > > > > two different compiled binaries. > > > > proc1 is started as primary process and proc2 as secondary process. > > > > > > > > proc1: > > > > Calls srcHash = rte_hash_create("src_hash_name") to create rte_hash > > > > structure. > > > > As part of this, this api initalized the rte_hash structure and set > the > > > > srcHash->rte_hash_cmp_eq to the address of memcmp() from proc1 > > address > > > > space. > > > > > > > > proc2: > > > > calls srcHash = rte_hash_find_existing("src_hash_name"). This > returns > > > the > > > > rte_hash created by proc1. > > > > This srcHash->rte_hash_cmp_eq still points to the address of memcmp() > > > from > > > > proc1 address space. > > > > Later proc2 calls rte_hash_lookup_with_hash(srcHash, (const void*) > > &key, > > > > key.sig); > > > > Under the hood, rte_hash_lookup_with_hash() invokes > > > > __rte_hash_lookup_with_hash(), which in turn calls > > > h->rte_hash_cmp_eq(key, > > > > k->key, h->key_len). > > > > This leads to a crash as h->rte_hash_cmp_eq is an address from proc1 > > > > address space and is invalid address in proc2 address space. > > > > > > > > We found, from dpdk documentation, that > > > > " > > > > The use of function pointers between multiple processes running > based > > of > > > > different compiled > > > > binaries is not supported, since the location of a given function > in one > > > > process may be different to > > > > its location in a second. This prevents the librte_hash library from > > > > behaving properly as in a multi- > > > > threaded instance, since it uses a pointer to the hash function > > > internally. > > > > > > > > > > > > To work around this issue, it is recommended that multi-process > > > > applications perform the hash > > > > calculations by directly calling the hashing function from the code > and > > > > then using the > > > > rte_hash_add_with_hash()/rte_hash_lookup_with_hash() functions > > instead > > > of > > > > the functions which do > > > > the hashing internally, such as rte_hash_add()/rte_hash_lookup(). > > > > " > > > > > > > > We did follow the recommended steps by invoking > > > rte_hash_lookup_with_hash(). > > > > It was no issue up to and including dpdk-2.0. In later releases > started > > > > crashing because rte_hash_cmp_eq is introduced in dpdk-2.1 > > > > > > > > We fixed it with the following patch and would like to submit the > patch > > > to > > > > dpdk.org. > > > > > > Could you send the patch in the mail? > > > > > > Learn how to send a patch: > > > > > > http://www.dpdk.org/dev > > > > > > Thanks, > > > Michael > > > > Patch is created such that, if anyone wanted to use dpdk in > multi-process > > > > environment with function pointers not shared, they need to > > > > define RTE_LIB_MP_NO_FUNC_PTR in their Makefile. Without defining > > this > > > flag > > > > in Makefile, it works as it is now. > > > > > > > > > > > > Please find here attached is the patch file. > > > > > > > > Thanks > > > > Dhana > > > > > > > > > > >
