On 5/20/2021 6:44 AM, Feifei Wang wrote:

Hi, Ferruh

Thanks for your comments.
Please see below.

quoted

-----邮件原件-----
发件人: Ferruh Yigit [off-list ref]
发送时间: 2021年5月19日 16:12
收件人: Feifei Wang [off-list ref]; John Griffin
[off-list ref]; Fiona Trahe [off-list ref]; Deepak
Kumar Jain [off-list ref]; Jerin Jacob
[off-list ref]; Herbert Guan
[off-list ref]
抄送: dev@dpdk.org; david.marchand@redhat.com; nd [off-list ref];
stable@dpdk.org; Ruifeng Wang [off-list ref]
主题: Re: [dpdk-stable] [PATCH v3] crypto/qat: fix uninitilized compiler
warning

On 5/17/2021 10:07 AM, Feifei Wang wrote:

quoted

In Arm platform, when "RTE_ARCH_ARM64_MEMCPY" is set as true,

compiler

quoted

will report variable uninitilized warning:

../drivers/crypto/qat/qat_sym_session.c:
In function ‘partial_hash_compute’:
../lib/eal/include/generic/rte_byteorder.h:241:24: warning:
‘<U35a0>’ may be used uninitialized in this function
	[-Wmaybe-uninitialized]
	241 | #define rte_bswap32(x) __builtin_bswap32(x)
	...

This is because "digest" will be initialized by "rte_memcpy" function
rather than "memcpy" if "RTE_ARCH_ARM64_MEMCPY" is set as true.
However,

How 'digest' is initialized by 'rte_memcpy'?

Firstly, 'digest' is initialized by rte_memcpy in partial_hash_sha_x function :
'partial_hash_compute' -> 'partial_hash_sha_x' -> 'rte_memcpy'.

If "RTE_ARCH_ARM64_MEMCPY = false", rte_memcpy will be defined as
'memcpy' to initialize 'digest' in  lib\eal\arm\include\rte_memcpy_64.h: 364, 
and compiler can identify this.

However, if "RTE_ARCH_ARM64_MEMCPY = true", rte_memcpy will be a inline 
function, and finally it will initialize 'digest' with two steps by invoking rte_mov16:
rte_memcpy -> rte_memcpy_ge16_lt_128 ->
step 1: rte_mov16(dst,src )
 step 2: rte_mov16(dst - 16 + n, src - 16 + n)
And the compiler cannot identify this multi-step initialization, then it will report warning.
 

OK, I got what you mean, thanks for clarification.

quoted

quoted

compiler cannot know it is initialized by the function.

To fix this, use "calloc" to initialize "digest".

Fixes: cd7fc8a84b48 ("eal/arm64: optimize memcpy")
Cc: stable@dpdk.org

Signed-off-by: Feifei Wang <redacted>
Reviewed-by: Ruifeng Wang <redacted>
---
v2: add check and free for memory dynamic allocation (David Marchand)
v3: fix compiler error

 drivers/crypto/qat/qat_sym_session.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/crypto/qat/qat_sym_session.c

b/drivers/crypto/qat/qat_sym_session.c
index 231b1640da..105a10957a 100644

--- a/drivers/crypto/qat/qat_sym_session.c
+++ b/drivers/crypto/qat/qat_sym_session.c

@@ -1190,8 +1190,7 @@ static int partial_hash_compute(enum

icp_qat_hw_auth_algo hash_alg,

quoted

 			uint8_t *data_out)
 {
 	int digest_size;
-	uint8_t digest[qat_hash_get_digest_size(
-			ICP_QAT_HW_AUTH_ALGO_DELIMITER)];
+	uint8_t *digest;

Will a memset 'digest' work too? Although not sure which one is better.

Thanks for your meaningful comments, I try to use memset and it is ok to solve this warning.
I will update this in the next version.