CODEWITHSUNDEEP
c
user2962885
user2962885

Reputation: 111

Can __thread can be used for a local variable

I have a function like this that uses static variable. Now i need to use it in a multi threaded application. 

char *
ether_ntoa(const struct ether_addr *n)
{
    static char a[18];
    return (ether_ntoa_r(n, a));
}

Can i use the __thread variable instead?

char *
ether_ntoa(const struct ether_addr *n)
{
   __thread char a[18];
   return (ether_ntoa_r(n, a));
}

I realize i can add another argument to ether_ntoa function, but was wondering whether this will work as well?

Upvotes: 3

Views: 131

Answers (1)

dbush
dbush

Reputation: 225227

Yes, this will work, but keep the static specifier. From the gcc docs:

The __thread specifier may be used alone, with the extern or static specifiers, but with no other storage class specifier. When used with extern or static, __thread must appear immediately after the other storage class specifier.

The __thread specifier may be applied to any global, file-scoped static, function-scoped static, or static data member of a class. It may not be applied to block-scoped automatic or non-static data member.

Upvotes: 2

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