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Subjectkernel list / container_of aka list_entry question
Hello list readers,

I have two questions and I'll keep them short

First one is about list_entry definition which is just a wrapper to
container_of with exactly the same arguments (namely, ptr, type, member)
whereas container_of is defined as follows

/**
* container_of - cast a member of a structure out to the containing structure
*
* @ptr: the pointer to the member.
* @type: the type of the container struct this is embedded in.
* @member: the name of the member within the struct.
*
*/
#define container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})


My question is why is there a '0' inside a definition?

The second question is why the following code generates errors
during compilation. list.h header file is included.

struct atheros_priv *priv = ieee80211_priv(dev); /* line number 141 */
struct list_head *iterator;


list_for_each(iterator, &priv->rxbuf.list) {
struct ath_buf *bf = list_entry(iterator, (struct ath_buf), list);

/* ... some operations on *bf here ... */
}

and errors are as follows

CC [M] /home/mb/atheros/transmit_receive.o
/home/mb/atheros/transmit_receive.c: In function 'ath_startrecv':
/home/mb/atheros/transmit_receive.c:141: error: syntax error before ')' token
/home/mb/atheros/transmit_receive.c:141: error: '__mptr' undeclared
(first use in this function)
/home/mb/atheros/transmit_receive.c:141: error: (Each undeclared
identifier is reported only once
/home/mb/atheros/transmit_receive.c:141: error: for each function it
appears in.)
/home/mb/atheros/transmit_receive.c:141: error: syntax error before ';' token
/home/mb/atheros/transmit_receive.c:141: error: syntax error before ')' token
/home/mb/atheros/transmit_receive.c:141: error: syntax error before '(' token
/home/mb/atheros/transmit_receive.c:141: error: 'list' undeclared
(first use in this function)
make[2]: *** [/home/mb/atheros/transmit_receive.o] Error 1


I'd appreciate if someone could help me with this problem.

kind regards
Mateusz Berezecki
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