[dpdk-dev] [PATCH] hash: fix memcmp function pointer in multi-process environment
张伟
zhangwqh at 126.com
Tue Mar 15 02:02:36 CET 2016
Thanks so much for your patch! Your patch exactly solves my bug. :)
At 2016-03-15 08:57:29, "Dhananjaya Eadala" <edreddy at gmail.com> wrote:
Hi
I looked at your info from gdb and source code.
From source code, rte_hash_lookup_with_hash / __rte_hash_lookup_with_hash() function doesn't invoke rte_hash_reset() function.
It may be possible that rte_hash_cmp_eq function pointer from one process is matching to address of rte_hash_reset () in other process.
For quick test, you can do two things.
1. just apply the patch I provided and recompile the dpdk with a -D flag "RTE_LIB_MP_NO_FUNC_PTR" defined and re-run your test
2. If it still crashes, disable the optimization in Makefiles and see, using gdb, how you are entering rte_hash_reset() from __rte_hash_lookup_with_hash(). this will tell you if it was a problem with function pointers in multi-process environment
Thanks
Dhana
On 03/14/2016 12:38 AM, 张伟 wrote:
BTW, the following is my backtrace when the system crashes.
Program received signal SIGSEGV, Segmentation fault.
0x00000000004883ab in rte_hash_reset (h=0x0)
at /home/zhangwei1984/timopenNetVM/dpdk-2.2.0/lib/librte_hash/rte_cuckoo_hash.c:444
444while (rte_ring_dequeue(h->free_slots, &ptr) == 0)
(gdb) bt
#0 0x00000000004883ab in rte_hash_reset (h=0x0)
at /home/zhangwei1984/timopenNetVM/dpdk-2.2.0/lib/librte_hash/rte_cuckoo_hash.c:444
#1 0x000000000048fdfb in rte_hash_lookup_with_hash (h=0x7fff32cce740, key=0x7fffffffe220, sig=403183624)
at /home/zhangwei1984/timopenNetVM/dpdk-2.2.0/lib/librte_hash/rte_cuckoo_hash.c:771
#2 0x000000000042b551 in onvm_ft_lookup_with_hash (table=0x7fff32cbe4c0, pkt=0x7fff390ea9c0,
data=0x7fffffffe298) at /home/zhangwei1984/openNetVM-master/openNetVM/onvm/shared/onvm_flow_table.c:104
#3 0x000000000042b8c3 in onvm_flow_dir_get_with_hash (table=0x7fff32cbe4c0, pkt=0x7fff390ea9c0,
flow_entry=0x7fffffffe298)
at /home/zhangwei1984/openNetVM-master/openNetVM/onvm/shared/onvm_flow_dir.c:14
#4 0x00000000004251d7 in packet_handler (pkt=0x7fff390ea9c0, meta=0x7fff390eaa00)
at /home/zhangwei1984/openNetVM-master/openNetVM/examples/flow_table/flow_table.c:212
#5 0x0000000000429502 in onvm_nf_run ()
#6 0x00000000004253f1 in main (argc=1, argv=0x7fffffffe648)
at /home/zhangwei1984/openNetVM-master/openNetVM/examples/flow_table/flow_table.c:272
(gdb)
I met a problem which I used the DPDK hash table for multi processes. One started as primary process and the other as secondary process.
I based on the client and server multiprocess example. My aim is that server creates a hash table, then share it to the client. The client will read and write the hash table, and the server will read the hash table. I use rte_calloc allocate the space for hash table, use memzone tells the client the hash table address.
But once I add an entry into the hash table, calling "lookup" function will have the segment fault. But for the lookup function, I have exactly the same parameters for lookup when the first time calls the lookup.
If I create the hash table inside the client, everything works correctly.
I put pieces of codes for server and client codes related to the hash table. I have spent almost 3 days on this bug. But there is no any clue which can help to solve this bug. If any of you can give some suggestions, I will be appreciated. I post the question into the mail list, but have not yet got any reply.
This problem is that in dpdk multi process - client and server example, dpdk-2.2.0/examples/multi_process/client_server_mp
My aim is that server create a hash table, then share it to client. Client will write the hash table, server will read the hash table. I am using dpdk hash table. What I did is that server create a hash table (table and array entries), return the table address. I use memzone pass the table address to client. In client, the second lookup gets segment fault. The system gets crashed. I will put some related code here.
create hash table function:
struct onvm_ft*
onvm_ft_create(int cnt, int entry_size) {
struct rte_hash* hash;
struct onvm_ft* ft;
struct rte_hash_parameters ipv4_hash_params = {
.name = NULL,
.entries = cnt,
.key_len = sizeof(struct onvm_ft_ipv4_5tuple),
.hash_func = NULL,
.hash_func_init_val = 0,
};
char s[64];
/* create ipv4 hash table. use core number and cycle counter to get a unique name. */
ipv4_hash_params.name = s;
ipv4_hash_params.socket_id = rte_socket_id();
snprintf(s, sizeof(s), "onvm_ft_%d-%"PRIu64, rte_lcore_id(), rte_get_tsc_cycles());
hash = rte_hash_create(&ipv4_hash_params);
if (hash == NULL) {
return NULL;
}
ft = (struct onvm_ft*)rte_calloc("table", 1, sizeof(struct onvm_ft), 0);
if (ft == NULL) {
rte_hash_free(hash);
return NULL;
}
ft->hash = hash;
ft->cnt = cnt;
ft->entry_size = entry_size;
/* Create data array for storing values */
ft->data = rte_calloc("entry", cnt, entry_size, 0);
if (ft->data == NULL) {
rte_hash_free(hash);
rte_free(ft);
return NULL;
}
return ft;
}
related structure:
struct onvm_ft {
struct rte_hash* hash;
char* data;
int cnt;
int entry_size;
};
in server side, I will call the create function, use memzone share it to client. The following is what I do:
related variables:
struct onvm_ft *sdn_ft;
struct onvm_ft **sdn_ft_p;
const struct rte_memzone *mz_ftp;
sdn_ft = onvm_ft_create(1024, sizeof(struct onvm_flow_entry));
if(sdn_ft == NULL) {
rte_exit(EXIT_FAILURE, "Unable to create flow table\n");
}
mz_ftp = rte_memzone_reserve(MZ_FTP_INFO, sizeof(struct onvm_ft *),
rte_socket_id(), NO_FLAGS);
if (mz_ftp == NULL) {
rte_exit(EXIT_FAILURE, "Canot reserve memory zone for flow table pointer\n");
}
memset(mz_ftp->addr, 0, sizeof(struct onvm_ft *));
sdn_ft_p = mz_ftp->addr;
*sdn_ft_p = sdn_ft;
In client side:
struct onvm_ft *sdn_ft;
static void
map_flow_table(void) {
const struct rte_memzone *mz_ftp;
struct onvm_ft **ftp;
mz_ftp = rte_memzone_lookup(MZ_FTP_INFO);
if (mz_ftp == NULL)
rte_exit(EXIT_FAILURE, "Cannot get flow table pointer\n");
ftp = mz_ftp->addr;
sdn_ft = *ftp;
}
The following is my debug message: I set a breakpoint in lookup table line. To narrow down the problem, I just send one flow. So the second time and the first time, the packets are the same.
For the first time, it works. I print out the parameters: inside the onvm_ft_lookup function, if there is a related entry, it will return the address by flow_entry.
Breakpoint 1, datapath_handle_read (dp=0x7ffff00008c0) at /home/zhangwei1984/openNetVM-master/openNetVM/examples/flow_table/sdn.c:191
191 ret = onvm_ft_lookup(sdn_ft, fk, (char**)&flow_entry);
(gdb) print *sdn_ft
$1 = {hash = 0x7fff32cce740, data = 0x7fff32cb0480 "", cnt = 1024, entry_size = 56}
(gdb) print *fk
$2 = {src_addr = 419496202, dst_addr = 453050634, src_port = 53764, dst_port = 11798, proto = 17 '\021'}
(gdb) s
onvm_ft_lookup (table=0x7fff32cbe4c0, key=0x7fff32b99d00, data=0x7ffff68d2b00) at /home/zhangwei1984/openNetVM-master/openNetVM/onvm/shared/onvm_flow_table.c:151
151 softrss = onvm_softrss(key);
(gdb) n
152 printf("software rss %d\n", softrss);
(gdb)
software rss 403183624
154 tbl_index = rte_hash_lookup_with_hash(table->hash, (const void *)key, softrss);
(gdb) print table->hash
$3 = (struct rte_hash *) 0x7fff32cce740
(gdb) print *key
$4 = {src_addr = 419496202, dst_addr = 453050634, src_port = 53764, dst_port = 11798, proto = 17 '\021'}
(gdb) print softrss
$5 = 403183624
(gdb) c
After I hit c, it will do the second lookup,
Breakpoint 1, datapath_handle_read (dp=0x7ffff00008c0) at /home/zhangwei1984/openNetVM-master/openNetVM/examples/flow_table/sdn.c:191
191 ret = onvm_ft_lookup(sdn_ft, fk, (char**)&flow_entry);
(gdb) print *sdn_ft
$7 = {hash = 0x7fff32cce740, data = 0x7fff32cb0480 "", cnt = 1024, entry_size = 56}
(gdb) print *fk
$8 = {src_addr = 419496202, dst_addr = 453050634, src_port = 53764, dst_port = 11798, proto = 17 '\021'}
(gdb) s
onvm_ft_lookup (table=0x7fff32cbe4c0, key=0x7fff32b99c00, data=0x7ffff68d2b00) at /home/zhangwei1984/openNetVM-master/openNetVM/onvm/shared/onvm_flow_table.c:151
151 softrss = onvm_softrss(key);
(gdb) n
152 printf("software rss %d\n", softrss);
(gdb) n
software rss 403183624
154 tbl_index = rte_hash_lookup_with_hash(table->hash, (const void *)key, softrss);
(gdb) print table->hash
$9 = (struct rte_hash *) 0x7fff32cce740
(gdb) print *key
$10 = {src_addr = 419496202, dst_addr = 453050634, src_port = 53764, dst_port = 11798, proto = 17 '\021'}
(gdb) print softrss
$11 = 403183624
(gdb) n
Program received signal SIGSEGV, Segmentation fault.
0x000000000045fb97 in __rte_hash_lookup_bulk ()
(gdb) bt
#0 0x000000000045fb97 in __rte_hash_lookup_bulk ()
#1 0x0000000000000000 in ?? ()
From the debug message, the parameters are exactly the same. I do not know why it has the segmentation fault.
my lookup function:
int
onvm_ft_lookup(struct onvm_ft* table, struct onvm_ft_ipv4_5tuple *key, char** data) {
int32_t tbl_index;
uint32_t softrss;
softrss = onvm_softrss(key);
printf("software rss %d\n", softrss);
tbl_index = rte_hash_lookup_with_hash(table->hash, (const void *)key, softrss);
if (tbl_index >= 0) {
*data = onvm_ft_get_data(table, tbl_index);
return 0;
}
else {
return tbl_index;
}
}
At 2016-03-14 10:16:48, "Dhana Eadala" <edreddy at gmail.com> wrote:
>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 function call 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);
>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.
>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.
>
>Signed-off-by: Dhana Eadala <edreddy at gmail.com>
>---
> lib/librte_hash/rte_cuckoo_hash.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
>diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
>index 3e3167c..0946777 100644
>--- a/lib/librte_hash/rte_cuckoo_hash.c
>+++ b/lib/librte_hash/rte_cuckoo_hash.c
>@@ -594,7 +594,11 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
> prim_bkt->signatures[i].alt == alt_hash) {
> k = (struct rte_hash_key *) ((char *)keys +
> prim_bkt->key_idx[i] * h->key_entry_size);
>+#ifdef RTE_LIB_MP_NO_FUNC_PTR
>+ if (memcmp(key, k->key, h->key_len) == 0) {
>+#else
> if (h->rte_hash_cmp_eq(key, k->key, h->key_len) == 0) {
>+#endif
> /* Enqueue index of free slot back in the ring. */
> enqueue_slot_back(h, cached_free_slots, slot_id);
> /* Update data */
>@@ -614,7 +618,11 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
> sec_bkt->signatures[i].current == alt_hash) {
> k = (struct rte_hash_key *) ((char *)keys +
> sec_bkt->key_idx[i] * h->key_entry_size);
>+#ifdef RTE_LIB_MP_NO_FUNC_PTR
>+ if (memcmp(key, k->key, h->key_len) == 0) {
>+#else
> if (h->rte_hash_cmp_eq(key, k->key, h->key_len) == 0) {
>+#endif
> /* Enqueue index of free slot back in the ring. */
> enqueue_slot_back(h, cached_free_slots, slot_id);
> /* Update data */
>@@ -725,7 +733,11 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
> bkt->signatures[i].sig != NULL_SIGNATURE) {
> k = (struct rte_hash_key *) ((char *)keys +
> bkt->key_idx[i] * h->key_entry_size);
>+#ifdef RTE_LIB_MP_NO_FUNC_PTR
>+ if (memcmp (key, k->key, h->key_len) == 0) {
>+#else
> if (h->rte_hash_cmp_eq(key, k->key, h->key_len) == 0) {
>+#endif
> if (data != NULL)
> *data = k->pdata;
> /*
>@@ -748,7 +760,11 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
> bkt->signatures[i].alt == sig) {
> k = (struct rte_hash_key *) ((char *)keys +
> bkt->key_idx[i] * h->key_entry_size);
>+#ifdef RTE_LIB_MP_NO_FUNC_PTR
>+ if (memcmp(key, k->key, h->key_len) == 0) {
>+#else
> if (h->rte_hash_cmp_eq(key, k->key, h->key_len) == 0) {
>+#endif
> if (data != NULL)
> *data = k->pdata;
> /*
>@@ -840,7 +856,11 @@ __rte_hash_del_key_with_hash(const struct rte_hash *h, const void *key,
> bkt->signatures[i].sig != NULL_SIGNATURE) {
> k = (struct rte_hash_key *) ((char *)keys +
> bkt->key_idx[i] * h->key_entry_size);
>+#ifdef RTE_LIB_MP_NO_FUNC_PTR
>+ if (memcmp(key, k->key, h->key_len) == 0) {
>+#else
> if (h->rte_hash_cmp_eq(key, k->key, h->key_len) == 0) {
>+#endif
> remove_entry(h, bkt, i);
>
> /*
>@@ -863,7 +883,11 @@ __rte_hash_del_key_with_hash(const struct rte_hash *h, const void *key,
> bkt->signatures[i].sig != NULL_SIGNATURE) {
> k = (struct rte_hash_key *) ((char *)keys +
> bkt->key_idx[i] * h->key_entry_size);
>+#ifdef RTE_LIB_MP_NO_FUNC_PTR
>+ if (memcmp(key, k->key, h->key_len) == 0) {
>+#else
> if (h->rte_hash_cmp_eq(key, k->key, h->key_len) == 0) {
>+#endif
> remove_entry(h, bkt, i);
>
> /*
>@@ -980,7 +1004,11 @@ lookup_stage3(unsigned idx, const struct rte_hash_key *key_slot, const void * co
> unsigned hit;
> unsigned key_idx;
>
>+#ifdef RTE_LIB_MP_NO_FUNC_PTR
>+ hit = !memcmp(key_slot->key, keys[idx], h->key_len);
>+#else
> hit = !h->rte_hash_cmp_eq(key_slot->key, keys[idx], h->key_len);
>+#endif
> if (data != NULL)
> data[idx] = key_slot->pdata;
>
>--
>2.5.0
>
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