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devsd: fix possible sdbio() race with inquiry data changing (due to ahci hotplug)

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the unit inquiry data might change in case the drive got pulled
with ahci. so keep track if we locked the ctl in a local stack
variable instead of relying on that the inquiry data stays the
same.
This commit is contained in:
cinap_lenrek 2012-12-26 17:53:12 +01:00
parent 7ceff03db3
commit 4a4c8218ee
1 changed files with 5 additions and 4 deletions
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9
sys/src/9/port/devsd.c
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@ -770,7 +770,7 @@ sdclose(Chan* c)
static long
sdbio(Chan* c, int write, char* a, long len, uvlong off)
{
int nchange, hard, allocd;
int nchange, hard, allocd, locked;
long l;
uchar *b;
SDpart *pp;
@ -832,7 +832,8 @@ sdbio(Chan* c, int write, char* a, long len, uvlong off)
poperror();
return 0;
}
if(!(unit->inquiry[1] & 0x80)){
locked = (unit->inquiry[1] & 0x80) != 0;
if(!locked){
qunlock(&unit->ctl);
poperror();
}
@ -854,7 +855,7 @@ sdbio(Chan* c, int write, char* a, long len, uvlong off)
if(waserror()){
if(allocd)
sdfree(b);
if(!(unit->inquiry[1] & 0x80))
if(!locked)
decref(&sdev->r); /* gadverdamme! */
nexterror();
}
@ -896,7 +897,7 @@ sdbio(Chan* c, int write, char* a, long len, uvlong off)
sdfree(b);
poperror();
if(unit->inquiry[1] & 0x80){
if(locked){
qunlock(&unit->ctl);
poperror();
}