Date: Wed, 25 Mar 2009 18:17:56 +0900 From: Weongyo Jeong <weongyo.jeong@gmail.com> To: Hans Petter Selasky <hselasky@c2i.net> Cc: Sam Leffler <sam@freebsd.org>, freebsd-usb@freebsd.org, Andrew Thompson <thompsa@freebsd.org> Subject: q: Memory modified after free in usb2 Message-ID: <20090325091756.GA14916@weongyo.cdnetworks.kr>
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Hello Hans :), I think porting uath(4) to usb almost have done that it works well to associate with AP and for WPA but I'm suffered from a strange panic after detach as follows: Memory modified after free 0xc4da3600(508) val=24000000 @ 0xc4da3600 panic: Most recently used by USBdev cpuid = 0 KDB: enter: panic [thread pid 17 tid 100036 ] Stopped at kdb_enter+0x3a: movl $0,kdb_why The detach step is like as follows: usb2_transfer_unsetup(sc->sc_xfer, UATH_N_XFERS); ... uath_free_rx_data_list(sc); uath_free_tx_data_list(sc); uath_free_cmd_list(sc, sc->sc_cmd, UATH_CMD_LIST_COUNT); that I've checked all memory leaks or calls after freeing memory but it looks it's not a driver problem. To solve this problem I modified codes slightly like below: usb2_transfer_unsetup(sc->sc_xfer, UATH_N_XFERS); usb2_pause_mtx(NULL, 5 * hz); ... uath_free_rx_data_list(sc); uath_free_tx_data_list(sc); uath_free_cmd_list(sc, sc->sc_cmd, UATH_CMD_LIST_COUNT); After adding it I couldn't see `Memory modified after free' messages anymore. My question is that I can't understand why adding usb2_pause_mtx() helps this symptom? regards, Weongyo Jeong
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